> Banning people is way easier on small servers

Big “citation needed” here. My bet is that Meta have far better moderation systems than any other social media company on the planet.

when i ran a fediverse server for myself and 3 people, but allowed public signups if someone came by; it was very easy to ban people, and very easy to null-route entire swaths of the fediverse, because i didn't want their content on my service.

That's more what i got from that pull-quote. I know a company that has hundreds of individual forums, and those are all moderated quickly and correctly (last i heard). They're moderated so effectively they often get DDoS by Russian IPs for banning users for scam posts from that country.