Sometimes people come in Writing.SE and ask questions that belong more in the WorldBuilding.SE.
Why isn't that an option in the section to close questions yet? (Close -> Off-topic -> migration)
Example: Ways to make money off trash?
Beta sites don't usually get custom migration targets. (We got EL&U as an exception to the usual rules, years ago.) The last time we looked there weren't enough questions flowing from Writing to Worldbuilding to make the case for another target, but I haven't reviewed the current data. In the absence of a custom close reason, you can always bring up cases on meta (like you've done) or flag.
The question you cited here would be closed on Worldbuilding as too subjective. The question doesn't give criteria for a good answer, so it's basically an opinion survey with no way to evaluate answers. That's on the wrong side of Good Subjective, Bad Subjective.