> I subscribe to a couple dozen subreddits, some of which are fairly large (/r/cooking, /r/games, /r/programming), and see pretty much nothing off-topic or political

Well, that's because those have specific topic. It's hard to make something political about cooking. Bit easier in case of gaming (as games being cultural work can be political commentary), I've seen some political discourses on r/programming as well.

But on r/all you will find post from more political subreddits (r/WhitePeopleTwitter, r/BlackPeopleTwitter, r/TwoXChromosomes, r/MurderedByWords, r/PoliticalCompassMemes etc.) regularly. For better of worse the posts consist mostly of content from left-leaning side of political spectrum, although it creates and echo chamber and you will be highly criticized if you try to raise any concerns.

I consider myself to be more on the progressive side, but sometimes when I see some post I have thoughts "wait, this one actually starts to sound like communism again".