HN is already struggling with losing valued members, mods, and contributions because of significantly more low value/high noise submissions and comments. As are many community sites (forums, advice, professional assistance).
Sites that don't ban and remove AI will become entirely AI, if that's your thing there's plenty of them around, why does HN have to morph into that? It resisted morphing into a self-promotion site (eg. ProductHunt, GumRoad), a crypto site, a security-vulnerability site (some exceptions), a political battleground (struggling), a blog repost site (some exceptions), a version release site, an unofficial big-tech support site.
I can still remember when they hired dang and he's still around, I see people posting I recognize from 18 years ago when I first started reading this site...
https://news.ycombinator.com/leaders
The youngest "top ten" account is from 2020, most of them are from 15-20 years ago. Two of the top ten have not posted for months, seven have posted today.
In fact, it might become legally required for web sites to accept AI writing in the near future just as it is for web sites to provide accessibility accommodations.
A more likely legal requirement is that use of AI is full disclosed, if it's even allowed. We're seeing the court systems say no, not only no but "the whole process was tainted by the use, and this is now a mistrial". There's likely to be professional repercussions codified soon - any professional practice governed by a recognized society (engineers, doctors, lawyers, pharmacists, some accountants) will either have to disclose use but accept liability or certify it wasn't used to maintain their professional status.
People are rejecting AI writing for good reason. I find it very unlikely Ai will improve much in this area any time soon