Let's just say your downvote on the original comment didn't make a dent, so much for a quick, unrepresentative poll. What I call Common Sense is ultimately no more than the essence of past UX research and can be obtained by a mere glance at what prevails in the grand petri dish.
Cf. Altavista/Google, Myspace/Facebook, and the rise of Apple for just a few major case studies in the area of UI clutter. With regard to the siren-song of social-lockin I'll recommend to study the fate of Ping, which exemplifies what happens when even the big guys try to go against the grain.
If you find a piece of formal "UX Research" claiming anything else then I'd be curious to see it.