"Hey can I borrow your chainsaw?"
"Sure, you need the gas powered one or the electric one?"
"Oh I'm not sure, which one would be best for cutting my hair?"
But part of the problem was they did know simple enough regex for what they wanted to accomplish. Having a few simple regex and some application logic around them would have done it. But they'd often think "that sounds messy, squeaky-clean can probably solve this in a single regex." And while I probably could, it would not be good code nor would it be more performant.
I wouldn't even have minded being seen as the "string pattern/parsing guy". But I was specifically regex-guy in their minds.
Also story for another day and another thread, I was also the MongoDB-guy. Similar to the regex stuff though, in 90% of the questions they'd send to me MongoDB was not the correct choice.
Overall it's more nuanced then could ever fit into an HN comment (yes I brought it up with management, and other issues), but there are a number of reasons I quit. I quit a couple months before a company buyout we knew was going to happen and I had equity. I felt like it was probably the right choice then. I recently got some beers with some of my friends who stayed through the buyout and had equal amounts of equity and learned I did make the correct choice.
90% of the time my answer was simply "Yeah... That's a bad use-case for a regex. You can use this java snippet to accomplish the same thing."
At the start I would actually solve their request with some hairy regex, but it generally did not perform well and when requirements change they'd be unable to edit it and would find me again to change it.