For me, think it's probably more your second idea, that we're not funneling media through a handful of TV channels, newspapers, etc. anymore like we used to. This creates (for better or worse) more of a "group think" mentality, since they've all seen the same tv shows and movies, and become more in sync with their views on all things, cultural, political... So people's sense of fashion is also in sync as well as the need to fit in.