Not welcoming assholes into your space isn't "far left" or an "echo chamber", it's just basic spam filtering.

Labeling everyone you don't agree with as an "asshole" is the sort of thing that usually leads to echo chambers forming.

When everyone they disagree with on anything substantive is an asshole, while accepting the same or worse behavior and tone if it aligns with their views, it's absolutely not "basic spam filtering".

You've missed the original point.

From the left's perspective, the liberals deserve muting and are spam, and same from the other way around. It's siloed echo chambers everywhere.

Part of it is unrealistic expectations of users thinking they're right about their world views. But part of it is platforms making features that amplify the former.