Most ardent leftists here can't contain themselves, get nasty, and get quickly zotted. However, it's not necessarily an echo chamber, either, since many right-leaning factions argue with each other all the time.
Actually, there is MUCH disagreement on issues such as the border, the war on drugs, correct grammar and spelling, etc.
By no means an echo chamber, from my perspective at least.
Ann C last night stated it pretty well -
most leftists, unused to having their ideology challenged, are unable to form cogent arguments, and resort to profanity and violence.