Then there is a single comment (not an answer) which says "you are not supposed to do that", which have received a single upvote.
You say "people won't bother", but in reality, 12 people have bothered and provided detailed solutions with code. What more could you want?
I don't really see the major problem here.
The second question has 23 answers, the top one having 186 upvotes. And then there is a single comment (not an answer), saying JS is more appropriate for this, and a reply from the OP explaining why it needs to be pure CSS.
Comments are for asking questions, request clarifications and providing information which does not constitute a regular answer. This seems to work exactly as intended. Several answers make it clear that the CSS solution is more fragile and worse supported than a JS solution, so I think it is pretty relevant to ask the OP (absent any information either way) if they couldn't use JS instead.
I really have a hard time seeing the problem here?