Plus the guy's thesis about "aligned interests" is glaringly contradicted by Reddit, where forums presumably coalesce around a common interest but are often toxic shitholes presided over by maladjusted mods who capriciously ban people for no legitimate reason; and even follow them to other forums and ban them there too.

The use of "toxic" to describe online behavior like this is perfect. Reddit actually and its ilk leave you feeling bad in every way.