It gives control to the node operator. You join a node on the basis that you like the operator and trust them to federate responsibly. The end user is along for the ride with the node operator.
That's not how it works in the case of WordPress though, in this case it's not posting to some account on someone else's instance, each blog is it's own ActivityPub instance (as they just add support for the ActivityPub endpoints to the existing hosting)
Mastodon suffers from the same problem Reddit does. Moderators have too much power.
A truly P2P system where the end user has 100% control over what is blocked, and furthermore where they can't be shut out in the cold by capricious mods, would be the ideal social media vehicle.
You can already control who and what you see by running your own server. If you choose to use someone else's infrastructure, don't act surprised when you're subject to their rules.
How many of these people are going through these blocklists to properly verify the claims?
And why should the users of my instance be penalized because someone found some reason to dislike me? If someone wants to block me, fine. But having the influence to push a whole server out of the wider network definitely counts as "too much power".
Users of an instance choose to place their trust in the instance moderator. If they feel they're being "punished", they're free to leave. It is insanely easy to change what instance you're on.
You're right, people do have the right to block whatever they want. But it's just shitty that someone else made the call, and now presumably many people are impacted. There's no recourse.