That's a fair question, and I agree that politics TOO is an echo chamber, although I would argue that "Leftist" is a little unfair. The politics stream is also a right-wing echo chamber, and my experience is that I would receive so few upvotes there or even so many downvotes that hardly anyone would see the meme at all. I still occasionally venture out there but less and less these days. Also, I'm totally open to fair criticism, and listening to other points of view, but I'm utterly sick of people swearing at me and calling me names, that I post less and less there. Cheers.
