The fediverse to which the most popular instances, such as mastodon.social, belong.

All the instances in the main fediverse have practically the same moderation rules and if you don't apply them to your instance they ban you and stop federating with you.

> if you don't apply them to your instance they ban you and stop federating with you.

A private party is not listening when they don't want to; And to be clear, you say that this is an intolerable imposition on your free speech?

Someone repeating a talking point but not understanding the words being used. Can pretty much dismiss those posts.

It seems reasonable to define the "main Fediverse" as the set of servers that most other servers federate with. There are distributed blacklists of servers like https://joinfediverse.wiki/FediBlock, and I would not consider the servers listed there to be on the "main Fediverse" since they cannot communicate with many of the larger Fediverse servers.