Sure but I'd argue there's a much greater chance of a subscription service having a fair and transparent process because you are the customer versus an ad-supported service because the advertisers are the customer.

And maybe users have a right to not be deleted without cause, despite it being a private platform. Maybe scale means that they have to play by different rules.

But what if the answer is reducing reach so only explicit followers can see what's posted? Do users have a right to being algorithmically boosted? Do they have a right to a wide audience? People who have had their reach reduced on instagram or twitter don't seem content to accept that but I don't see an argument against it.

In a federated system, spam and bots are a huge problem. One way this is handled is a shared blocklist. Something I toyed with was a propagated list like DNS to handle this problem, which would go a long way, but would also mean that being blocked by a highly trusted node could mean being blacklisted by the fediverse. This has already happened in a soft way when Gab was mass defederated. As the fediverse grows, automated tooling is necessary. Even if people have a right to contest being blocked, what's the reasonable mechanism for getting unblocked in a massive federated system?

I can see it from the point of view of e.g. a politician, where reduction in reach has a direct impact on the number of votes they can expect. Disadvantaging one is as good as giving advantage to the rest, and in the context of politics that would be problematic even if a court ordered it.

That's not to say Fediverse-style moderation would solve this. I don't really know what the solution is for algorithmic feeds. Personally I'd rather go back to lightly-federated or unfederated forums, but that idea seems sadly unpopular.

Right and I'm not a fan of algorithmic feeds at all. Social media users broadly are happiest with a basic chronological feed composed only of who they follow. That's why every social media platform starts with that, then adds algorithmic feeds when they want to attract advertisers and after they feel their users are "locked in" enough.

Especially when engagement is the primary metric, which incentivizes our worst attention-seeking behavior. Well thought out, nuanced posts get lost in the ether. Hot takes, trolling and extreme positions get pushed to the top.

Reddit and HN mitigate this somewhat with the downvote system, which is hardly perfect, but at least means negative feedback is not given a positive weight in rankings.