1. Market
2. Gaming experience
Steam users or console owners have spent time, money or both just to have the equipment to play games. I'm guessing that the same market that buys consoles buys smartphones, so they may be more likely to buy good phone games. But maybe not! I mean, they have a console at home so if a game they want is cross platform maybe they prefer to play it on that?
The gaming experience is also hugely different. They are converging, but there are still so many differences. That blazing fast new processor doesn't do much for controls, screen size, battery life, multiplayer - all of these are things that stop phones from competing with consoles directly. My guess is this is a reason that the top games are time wasters.