The media has almost given new generations an a.d.d-like syndrome where we are completely incapable of paying attention to one thing for a long period of time. Not only has the media created this “syndrome” but they feed to it, they only tend to put things out that go along with the current trends of the year..month..week..whatever. They take the first thing that gets attention and recycle it in every way possible until it gets old. Then they find the next big thing, rinse, and repeat. I think this is the main reason we don’t have any more superstars, because agents aren’t really looking for long-lasting talent.
I don’t think audience fragmentation has too much to do with the lack of superstars. It does specialize things more, but I would think it would make it easier to reach fame, maybe not super stardom, but truth be told too much fame seems to do more damage than good. As for fragmentation taking away society’s sense of community, it doesn’t really seem like an issue because that many people can’t truly be unified. In fact fragmentation probably brings multiple smaller groups closer together. Liking different things shouldn’t be a reason to pull people apart, it gives people different things to tell each other, it keeps things interesting.