They were writing an article about how Facebook gained another $5 billion in valuation every other week. Who else writes articles about valuations of a (still pretty random at the time) company every 2 weeks and about each incremental rise? I don't think I've seen that ever before, even on BusinessInsider, and they do a bit of that, too.
I may be exasperating a little, but Techcrunch was a pretty powerful force in the tech world then, and I do think it influenced valuations and put them on a feedback loop just by writing about them every 2 weeks, on how Facebook's valuation grew another $5 billion, and then that would influence investors and help it gain another $5 billion. Not to mention TechCrunch was also one of the very first sites to use Facebook comments. So although I'm not reading TC these days, I'm not surprised that you've noticed that.
I'm not sure if manipulation of stocks is legal like this or not - though it certainly would highlight why high viewership media are valued so highly by less-than-honest people.