I agree with just about everything you said excepting your implication that communities that lean further left are not as welcoming to communication (shunning opposing views).

I don't argue that doesn't happen, but I don't think it's isolated to one end of the spectrum. I would bet the symptoms are the same at either extreme -- right or left.

If you mean "center-left" when you say right, I think what you're actually implying is communication is better tolerated in communities with more balance between political viewpoints, and less given to extremes.

But traditionally, outside of movements, it's been somewhat bad form to bring politics into the pub at all.