There's a fundamental lack of trust in people with these protocols. That's exactly it.
Crypto assumes that everyone is an attacker and that nobody can be trusted, and so we need 'proof' of your actions.
Bluesky assumes the same, that you should have to prove that each social media post is yours cryptographically.
And the fact is just that that's not necessary. Mastodon's system works while requiring trust, and it scales remarkably well in an anticapitalist way.