A recent question, Does it look unprofessional to have my name and all the titles of my website in lower-case?, was closed as being off-topic. I myself voted to have it closed as off-topic, since I saw it as more of a design-related question.
However, in the comments, @patrick notes that "He's not asking about design (placement, position, color, font, white space, etc...); he's asking about capitalization and as Smithers pointed out, the "hi, there" is bad writing because it makes the content seem like a header."
This made me think more about the question. I still think it's design related, however in a more specific sense, it is a typography question, which makes it related to writing, and is similar in nature to questions about font colours, types of fonts, line heights, font spacing and so on.
While you could consider typography as being part of design, I struggle to understand why this question would be different to, say, asking a question about whether or not to use the Courier font for a manuscript. There are probably other questions that can be considered to be typographic in nature that have been allowed before.
The only real differentiation I can make, is that one dealt with printed media, while the closed question is to do with a webpage, but that must be a superficial distinction, surely?
What am I missing here? When do we allow one type of typographic question, but not another?