I’ve just found an oldish link on TechCrunch:
Have read it, and still I can’t help but ask the question of “why?”. I (hypothetically) log in to Amazon and see a list of products my friends have “liked”. That’s all well and good (?), but what are the chances of that matching the reason that I’m on Amazon? Surely if it doesn’t, it’s just clutter. I go on there looking for a kettle, and find that 5 friends have all “liked” a pair of trainers. Which is absolutely no use to me. I just don’t get it. The world seems to be creating interfaces between every system just for the hell of it, with no consideration as to how useful any of it is.