And then there’s the echo-chamber problem. It turns out that when people have an option to avoid dealing with ideas they disagree with (even slightly), very many of them choose that option. IMO this is a major (perhaps fatal) problem with social media. The fediverse is not magically immune from it.

Yeah. Federated social media is even more prone to this effect than centralized. This is the single reason why I believe Lemmy can’t possibly become anything meaningful on a global scale. It is a purgatory built in the image of long dead websites where we all wait for the rotting corpses of old media to wither away.