That's a pretty naive view that probably has more to the way the labels work than the artists. Most of the smaller 'passionate' artists spread through word of mouth. Once they spread to the UK from America, they are probably going to be pretty big. Meanwhile, the labels just pick the most accessible songs so of course you are going to hear those more.Animal Collective, Vampire Weekend, Best Coast, Death Cab for Cutie, Foster the People, Grizzly Bear, Warpaint and LCD Soundsystem are examples off the top of my head.