so much depends on how well the Admins of each instance manage these things. Plus there will be a lot of churn
Outside of journalists & financial traders (along with *really* fringe political movements) there may not be a huge market for up-to-the-minute microblogging.
And arguably the single best filter for many forms of niche community websites is requiring payment for access. Require a recurring payment to participate and most forms of trolling & other disruptive behaviors disappear. Charging for access aligns incentives & acknowledges the cost of running the site, the moderation, dealing with churn, etc.
I don't think the problem is technical barrier to entry, but largely one of incentive structures.
There still are tons of forums & niche blogs on the web, but over time they tend to keep losing out to the likes of Facebook & Twitter. Many communities with staying power are ultimately more about depth of discussion rather than speed of analysis.
And sometimes charging for something makes people value it more. Which could make a once a week or once a month community site that is freely accessible become part of a daily routine if the owner charged for access.
