What's cool about the fediverse is that we get to choose.
Do I want to be in an instance that federates with everyone, good and bad?
Pros:
More content.
Potentially insightful debate.
Cons:
More negativity.
Potentially giving a platform to extremists.
Or do I want to be in an instance that defederates on a whim?
Pros:
More positive content.
Taking a strong stance against extremism.
Cons:
Less content.
Potentially missing insightful debate.
Personally, debate I've had that was insightful was generally in good faith to begin with, and would be allowed on platforms like Beehaw, so I don't see much use for "anything goes" kinds of platforms. Additionally, I'm not always in the mood for debate. I can just switch between different instances depending on my mood. Given that everyone can choose their instance, I don't see much of a reason for trying to federate with everyone.
I haven't seen much in the way of actual debate, more 'soviets good west bad, da comrade!'
There's nothing to be gained from arguing with crazies and naive college students. Had my fill of those types on reddit. Now I point and laugh until I get too annoyed and I'll find a new instance