Fediverse has plenty of servers which are "free speech" adjacent, which most Mastodon servers close off since its easier for them to police what their users can see than let them do it themselves. The vast majority of them do not run the Mastodon software, and feel far more "wild west" with all the shitposters. But if you want to talk with actual hackers and are into that sort of thing, it's fun times.
They'll include reasons for the block, which you should pay attention to.
As far as reasoning goes, I think you can grasp how people would try and wield a tool like blocklists. A lot of blocks are merited, while some arent. I've had several blocks put on my instance from servers that I never even interacted with, for reasons that seemingly appear out of thin air.
Most instances of trolling can be dealt with by a single block, or reaching out to the admin, but basically no one puts in the effort to reach out if someone's causing problems (Hell, one guy even reported my whole site to my host without so much as a word in my direction, just for a couple inflammatory posts someone made).
And I don't think it's right to police what people are able to see and interact with if I'm running an instance with other people (if it were a single-user instance, that'd be different).
But hey, it's your server. You should do what you want with it. I just wanna do what I want with mine.
You can browse by software, whether its open registration or not, allows tor, etc. You can glean statistics off of certain instances, which is really useful if you run one yourself. Most of the instances on the other side of fedi run the Pleroma software.
Have fun!