I actually agree with you here. My first thought was the anarchist communities here. Sometimes I agree with the sentiment of a post there, sometimes I don't. I think we largely agree on a rough framework of the world, though, which is, like you said, different from the complete inability to agree on the fundamentals.

Summed up perfectly why I left Reddit for here.

one thing i have noticed here is that often people will engage in actually productive discussion even if they disagree. I also welcome being corrected, often that is the best thing here since it lets me actually learn/correct something with my thoughts.

And most people here live in a city and work in IT. Like, take the 10% of your area that agrees with you the most and there's going to be vastly more diversity of thought and opinion.

You know what they say about thinking everyone else is an asshole...

The tankie instances seem full of people without empathy, so that's a start I guess if you want more sociopaths...