I've often wondered this myself; I was pretty firmly embedded in the punk, new wave, then post punk world of Manchester in the late 70s, early 80s. Back then it seems that scenes almost had to be small and cohesive in order to develop at their own pace without too much outside intervention, free from overbearing commercial exploitation. It seems to me that in the current everything connected, rapidly evolving, diminishing lifetimes, everything monetised culture, what previously was a movement is now merely a trend.