Noone complained we can't discriminate DC IPs, though to be fair some (imo bad) operators did just that. This is not even about preventing bots, which has perfectly legitimate usecases (eg. Internet Archive).

This is about filtering out bad bots/actors who have no respect for your resources and will drain all of it causing bad experience for everyone. But because they know they don't respect robots.txt or even simple rate-limiting, they have to employ so-called residential VPNs. They're residential in that they route through real user connections, and so you can't block the IP/subnet without dropping a certain amount of legitimate human-driven traffic.

Personal example: some time ago, i had to disable a wordpress plugin on a site that was causing 100% CPU usage on the whole box (hosting dozens of wordpress instances). That plugin was a simple calendar, but a bot was repeatedly scraping non-existent (or rather, "no event planned for this day") pages for every date in the calendar that you can represent in the DB timestamp, clearing the cache as it went to try and find new events for 1000 years ago. Whoever operates this IP space doesn't matter to me, i'd just like to block them because they don't respect robot.txt… but i can't because they use a "residential proxy" and will change IP address every hour or so.