Interesting post. I don't know if he foresaw it, but another factor is the importance of the teeny bopper segment. I would like to verify this before forming a theory. But I remember that when I grew up, I used to listen to what music my parents bought (which is how many older prog rock listeners on this forum have described their childhood experiences) but by the time I was around 16 or so, their purchases began to taper off and I started following music not related to their tastes. But a lot of my schoolmates probably broke off by the age of 10 or so and the industry may have tried to get out music that served their needs specifically. I believe that is possibly the cause of much heartburn among listeners - it is not about whether the music is good or bad, a lot of it (the mainstream stuff) is probably not intended for the late 20s/early 30s demographic (or older). I find it hard to imagine a late 20s working professional also being a Belieber, for instance.