A while back I noticed that .biz specifically has its own checkbox in the o365 spam controls. And sure enough I don't think I've ever done legitimate business on a .biz. I wonder what the heck happened to it.
The only .biz I've ever interacted with is Minimus.biz, and it looks like they've barely touched their site since 2006. Just the way I like it, honestly.
Sending a .biz link in an SMS will be blocked by Google, and the sender won't be informed the message was not sent. Cheap domains are cheap for spammers too.
Other than that, yeah, it's a cesspool.