Tech's got a blind spot, and its name is “us”
This, perhaps, is the failing of Twitter, and one of the strengths of federation, in that what we need are technologies which enable people to support their existing communities, or ones they wish to create, while then also providing bridges into other communities and wider, more general streams of “content”. The model behind Twitter somehow thinks an unfettered river of such “content” alone is good enough.
I suspect that while we can call people interacting with screens “community”, if that's not what evolution has encoded our neurobiology to consider community (i.e. community in more than merely a conceptual sense), then it's just plain not community in the way that matters most.
Sites that are fundamentally about ads (and, really, that's typically what “scaling” is all about: adding more and more eyeballs for what advertisers are serving up, not for what users are doing) perhaps can never also fundamentally be about any sort of community for which it would be worth using that word.
Yes, that's arguably an order of magnitude more removed from neurobiological community than the aforementioned.
In time, however, the site began to espouse the worst of the internet—Urban Dictionary became something much uglier than perhaps what Peckham set out to create. It transformed into a harbor for hate speech. By allowing anyone to post definitions (users can up or down vote their favorite ones) Peckham opened the door for the most insidious among us.
Like so many who gush over the possibilities of the internet for the species, Peckham apparently didn't understand that no amount of attention to the details of internet technology can compensate for – let alone fix – broken people.