Assuming that you find a site that isn’t extremely overpopulated (I’m looking at you, MySpace, Facebook and Twitter) that you’d get too much competition, it would be okay.
But you wouldn’t want a site so underground that you got no views or followers (‘cause where’s the fun in that?)
It’s all about finding a balance: population versus competition.
The internet is a feeding ground, much like the Sahara: if there are too many lions and not enough gazelles, competition is going to arise—although we lack the ability to physically kill our opponents—we can find new hunting grounds, however…
I believe social bookmarking sites are great in getting your articles and blog posts out - also they're good for activists and reporters to get their messages out to the outside world. Places like Twitter, Facebook, Digg and Stumbleupon have a massive global audience. Even the Iranian protesters inside and outside Iran are still using Twitter to promote their pro-democracy campaign.