I simultaneously think this is true and a massive contradiction. A right and a left winger posting on a thread about J6 would both come away convinced of their rectitude, despite actively disagreeing about everything. There is almost no boundary of agreement over facts or intent, just an active disagreement online.

Selection bias is the most powerful force known to man, or life for that matter. An Internet where every voice is represented is an Internet with billions and billions of ways for selection bias to make you happy.