It really doesn't matter what the questioner wanted. The main utility of sites like Stack Overflow is not to give this one person the answer to their specific p

It really doesn't matter what the questioner wanted. The main utility of sites like Stack Overflow is not to give this one person the answer to their specific problem, but to be a useful landing page to people searching for things related to the question later. A lot of those people are novices when it comes to regexes, and it's useful to make it clear that there's some things that are better solved with other tools, even if you can abuse extended regexes syntaxes to solve them.