I sometimes get booted after a set, perhaps for skill level?? I am in the top 1% of RB3 xbox scores for Guitar and Bass, but am not one of the super awesome players who ace difficult solos, etc.
I started playing rhythm music games after RB3 came out, and I also realize that the leftover players now are probably almost all in the top 5% or so.
I only boot someone if they are obviously less skillful but insist on playing guitar EVERY time. A drummer or singer I pretty much never boot (unless there is feedback from their mic which makes the songs mostly inaudible).
So if you are doing quickplay and playing with randoms, at what point do you draw the line?
I have about 350 songs total, so perhaps some people boot me because they want to play with the 1500 song people? But most of the people I get on Quickplay don't have even 1/10th of the DLC that I have, and the likelihood of them having a bunch but just not having any of mine seems remote.