I've run into that as well. I'm amazed that popular ad blockers still do that, since it's obviously trivial to work around for actual ads, and will result in so many false positives.

They do it because it works.

That's a hilarious comment, and a good point. But you can tell when your ad blocker is messing with site functionality beyond just blocking ads (i.e., the false positives your parent comment mentions). And at a certain point, this is a differentiator among the ad blockers.