> now you’ve got a big juicy target maintained by hobbyists.

You'd have a much larger number of targets which makes things somewhat more difficult for those looking to exploit them since they'd have to track down the various platforms and navigate a variety of systems each with their own rules and culture. Fewer of them would allow ads at all and none of them would match facebook in terms of being as easy to weaponize. "Pay us to attack this platform's userbase" is a core part of facebook's business model.

You'd also be much better off when the people maintaining the system are hobbyists because they actually care about the platform and moderation. That's a massive improvement over facebook which does as little as they possibly can, only enough to be able to claim that they do "something" at the next congressional hearing, while still making sure that they can actively censor what they want. Moderation on major social media platforms seem to frustrate the efforts of legitimate users more than spammers and scammers.

I'd put my money on "Randall, the over-worked sys admin" over the half-assed AI moderator bots employed by Musk and Zuckerberg