it's the old community chicken & egg problem, people go for the comments, but unless there are enough 'seed' users the comments aren't there to attract the others. Then along come the trolls and disruptors and before you know it, the community forks and the whole process starts over.
Lobste.rs has an interesting way of handling the influx of trolls and such by making the site invite-only. If someone ends up being banned, so does whomever invited them.
The thinking there is: Only links about development of software, no entrepreneurial stuff.