Trolls are a big problem in decentralized social networks, too. I think the difference that strikes me is the ability for members to define and enforce (or at least try to) their own content moderation policy.
Centralized networks are too big to have a policy that works for everyone, and too big to enforce that policy. Decentralized networks push that labor to the "edges" of the network.
Still plenty of problems in decentralized networks, as PoC fediverse users can tell you.
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