You can see the Hot Network questions here. As of writing this your question is on the third page and is therefore shown all around the network, which means that other users might see the title and think it's interesting, so they check it out. And everyone with more than 200 reputation on any site of the network gets the association bonus of 100 rep when joining another community, which unlocks basic privileges like commenting and upvoting.
There are lots of discussions about the Hot Network Questions. For example many people don't want to see any on the right side of their site. There have also been a lot of discussions about implementing features that act similar to the Protection feature (10 on-site rep required to answer; association bonus doesn't count) so that for example voting on HNQs would only unlock after 15 on-site rep.
What's important is to look at What is the Goal of “Hot Network Questions”? The idea is:
The goal of the hot questions should be to drive up interest in the site. The hot questions should be a lure to encourage SE network users to contribute to other content, not just do a drive-by on the hot question.
But looking at what Shog9 has to say about this topic:
Don't get me wrong: a big part of the SE 2.0 model for site creation relies on folks having a wide range of interests, and jumping at the chance to participate in sites dedicated to those interests when they emerge. I have no doubt that pervasive, network-wide "hot" lists help in this goal, but calling that the primary purpose is akin to saying the primary purpose of convenience stores is to fund The March of Dimes.
That discussion also has some ideas that look like they might be helpful for what you have in mind, like here (no emphasis added):
Allow Removal from the List
Give trusted users (10k or 20k+) the ability to remove posts from the hot questions list. For whatever reason, if a question shouldn't be on there, the community should be able to purge it.
I would suggest allowing a tag to be added to posts that prevents it from showing up on the list, like a mod tag, but accessible to trusted users too.
Currently, as far as I am aware of, there is no way to opt-out - neither individually, nor as a whole site.
Personally I think that the HNQs are doing a good job of bringing people to the site. New users bring new perspectives and potentially new interesting questions and answers. Most of the people are looking for a distraction - they see something interesting and want to check it out for a few minutes. These people are what you seem to refer to as "noise". They are going through the question, voting a bit, maybe writing a comment and then they are probably gone. At least until the next interesting HNQ pops up. But I don't see too much harm in that in general. Random people interacting with questions and answers increases the amount of perspectives that look at the questions and answers and can potentially increase the quality.
And if there are low-quality entries, for example because an opinion-based question hit the HNQ and people are dropping low-quality duplicate half-answers - well, users with enough rep or mods can protect the question and end that. It's a bit more traffic than compared to the usual question on the site, but nothing out of the ordinary. And if these people don't bother to read the on-topic rules of the site where they just registered, maybe their answers get deleted.
I think we should not add a feature to opt-out, which is why I am downvoting this feature-request. I don't see big problems with the current setup and I think that the increased traffic is overall good and healthy for the site. Adding the possibility for single users to opt-out would probably mean quite some time for implementation and I am not sure if that is a good idea overall. It feels like wanting to close off the community from the rest of the network.
I wrote a bit about the comments to your question you mentioned, as I did in the original post from you here.
The first one, that got deleted by now, was something like "I would expect you to write about that Alex guy." I can only speculate on the intention of this user, but maybe he was trying to point out that the name Alex can be used for male and female characters alike in some languages. Anyway, it wasn't really explicit if he had any intentions and it didn't add anything to the question about how to write a useful "blurb". Comments are ephemeral on StackExchange and can be deleted at any point for any reason - just flag stuff like that as "No longer needed."
The second one was pointing out what he perceived as a typo. As he doesn't have the reputation to edit posts and there is a character limit of 6 characters that need to be changed at minimum he left a comment. I think that's a nice thing to do. Maybe it's because I am not a native speaker myself, but I think that it would be nice to point out to him why that is the correct word you used or edit your post and then flag the post as "No longer needed" - you acted on it after all. If it's obvious to a native speaker why that word is correct simply go to the flagging and be done with it.
The third comment was trying to clarify the usage of the word. Judging by his profile he is quite active on English Language & Usage, so it's quite natural that he would try to clarify this aspect. And that's what comments are meant for - clarifying things in the question. If the word you used is correct then explaining to this new user why it's correct as you did is the correct thing to do. We want to be a welcoming community after all. The comments could then be left there for future readers with a possibly similar confusion or be flagged as "No longer needed" after some time, as the need for clarification is not there anymore.
The first comment was quite useless, but not really trolling. It looked like a failed attempt at being funny to me and the other two seemed actually useful in the sense that comments are supposed to be used for this stuff. In that sense they did contribute to the question by trying to improve the information that future readers will find when reading your question.
Your notion about WorldBuilding.SE is quite difficult, especially because your criteria match only one person and by taking half a minute it's easy to find out who that is... I don't think attacking users is a good thing to do and saying that this user didn't contribute as they haven't asked a single question is not okay. There are lots of ways you can contribute to a site. Asking, answering, commenting, welcoming users, editing, voting, flagging, ... For more information about my stance on this you can read my answer to the question What does being a 'Contributor' look like on Worldbuilding? Only answering is not making you automatically a troll and you are still exposed to comments. SE is protecting relatively good against trolls as you need a minimum of rep to even comment somewhere, let alone VTC or do other things.
I also don't see what "BASIC user-content block controls that every other online community has" you mean. I have never encountered a community that could block trolls before they posted a comment that aims to ask for clarification on a term for example. There were times when I wished I could block a single user (two in fact over my time here on StackExchange), but most of the time it was enough to act on their posts like I would act with every other posts - voting (up or down), flagging if not appropriate, VTCing when I think that a question should not be answered on the site, flagging for moderator attention when I encounter something rude, ... Our mods are really, really good at handling all sorts of trolls. It might take some time, but in the end I haven't encountered trolls a lot here - not by a long shot as many as on other forums.
The thing is: getting away from the HNQ won't save you. It's just that there are more people interacting with your questions/answers. The more a site grows the more people there are interacting with your stuff. And the amount of experience varies. You will always encounter new users that need to learn the basics. And there will always be people that have harsher criteria for some things. More people simply mean more chances for someone needing help - because if someone doesn't know a term is used correctly they need help and we are all here to help others.
There are fewer closed posts here and fewer problems - which is partly simply because there are fewer posts in total. Yes, according to the mod tools in the last 30 days WB had a close rate of a bit over 40%. But Writing had nearly 30%. That's not so terribly far away. And WB had 436 new questions while Writing had 164. You would see far more closed questions here - if there were more questions. And as there are fewer questions and fewer answers and fewer users there tend to be less problems. The biggest problem as far as I am aware of seems to be the lack of questions, which is why Writing hasn't graduated so far though there is a definite consensus among the users that Writing should graduate .
If you are really bent on not wanting new users to interact with your questions the easiest thing would be to protect them as soon as possible (3.5k reputation feature here; mods might be able to help you), though that would hardly be an appropriate use of this feature and would not block of comments. Another way would be to make sure your question doesn't reach the HNQ, though that's probably even harder. You can see the way "Hotness" is calculated, for example on Chemistry.SE. Or taken from here:
(MIN(AnswerCount, 10) * QScore) / 5 + AnswerScore
MAX(QAgeInHours + 1, 6) ^ 1.4