My dream of social media utopia is that that we see a nonprofit organization who makes no bones about their moderation policy and enforcement or their revenue and expenses. I think centralization is just the only way a network can grow to useful size or behave predictably. It's not really a social network, but my model for this is Wikimedia. They've built something incredibly durable, centralized, aggressively moderated and financially viable.
>we see a nonprofit organization who makes no bones about their moderation policy
The problem is that the rules will be made by humans and will be enforced by humans. This will never be even close to perfect, especially with bad actors which are inevitable when a platform gets popular enough.
I don't think the goal should ever be "perfect". The problem I see with any commercial endeavor (this is probably as sideways critique of capitalism) is that if you have profit as the superseding interest, it will always be in conflict with being fair or being inclusive. At the same time what someone like Elon Musk clearly doesn't understand is the fundamental conflict between having an environment that fosters fruitful conversation vs absolutist free speech. Just having a platform that has a clear number goal of "free sharing of information and idea" at the top says clearly that it will come before platforming troublemakers or letting advertisers put their finger on the scales.