Being inundated with techcrunch articles is just a symptom of the real problem: there's no cost to submit articles, and there's potentially major karma in being first to submit an article that other people will also submit. Therefore, some people will submit anything they think others will, just to be first. These duplicate submissions also upvote the articles, pushing out better ones.

One option would be to make submitting posts cost a few points karma, as an experiment. I suspect the quality of posts on the frontpage would improve overnight, as interesting posts wouldn't fall off the frontpage within an hour, drowned out by gossip.