They aren't blocking anything. They are just asking nicely not to be crawled. Given that AI companies haven't cared a single bit about ripping of other's peoples data I don't see why they would care now.
Prostate and rectal cancer is real, boys. Grow tf up about it.
I suspect that AIs are already more effective than humans at passing captchas.
*edit: added "for-profit"
If something I worked on turned out to play a significant part in something that turned out to be that big a deal, I'd be OK with it. And nobody's stopping people from doing web-search studies with it, to this day.