Maybe because of PS Plus and maybe not every ps3 owner buys ALL the main stream games.
For example: american people buy a lof of shooters right? European people a bit less, in some genres american sales (country with more 360s sold than ps3s) have great impact worldwide in my opinion. I think ps3 players have more different tastes among them. (sorry if there are some grammar mistakes)
Persona 5 on PS3, I won't need next gen!