I think that every question about he usage of the comma in a particular situation is either fine or can easily be turned into a non-opinion-based one. In each such case, there is a small amount of arguments for or against using a comma (often only for one side) and a good answer can provide them. Like every other question asked in a prescriptivist mindset, we can answer it in a descriptivist way, even without being explicitly asked to do so. You could even go so far and claim that if such questions should be closed as primarily opinion-based, so should everything else on this site.
That being said, I can imagine questions on commas that are opinion-based beyond hope like:
Is using more commas than necessary a sign of character weakness?
but those are clearly different from your typical comma question and closing them is hopefully not a matter of debate.