Reddit communities live and die by the strength of their moderation. Sure, Reddit as a whole is mountains of garbage. But the beauty (if that's the word) of the subreddit system is that to folks who want to talk about communism, hating women and minorities is garbage, and to folks who want to hate women and minorities, communism is garbage, and they both get the experience they want.
Reddit's popularity is due to the fact that a) people have multiple interests and so they want to hop communities with low activation energy (same high-level reason that GitHub got popular over individual git hosting sites: you already have an account) and b) there is some correlation between being a "bad-faith actor" across communities, regardless of their specific moderation worldview (e.g., neither /r/GamersRiseUp nor /r/FULLCOMMUNISM is interested in V1agr4), and so "you have some karma at all, regardless of source" is a useful filter.
> Once again, if you were right, twitter, reddit, facebook, etc wouldn't have grown to what they are today.
All of these systems put work into blocking abusive participants site-wide (including real humans who are very carefully and intentionally spewing vitriol) and are increasingly automatically blocking them.