Was talking about Mastodon with an old-school sysadmin guy. We reached the realization that defederating from instances with no/bad moderation is essentially the same thing as blocking open relays back when you ran your own email server: open relays always end up getting used for spam, you block 'em to protect your users.
Email was and still is the first federated social network, so it already faced a lot of the same problems; we should study its solutions (and its failures).
The social network of the future: No ads, no corporate surveillance, ethical design, and decentralization! Own your data with Mastodon!