And unlike console and pc gaming, there's very little overlap in audience and games. You cannot convince someone who has a pc or console that their phone is the device they should be pulling out to play games on. So even if they are say on a bus or a train, you cannot get them to buy a full-priced game on their phone, because they'd rather wait and play it at home. Instead it's free, short, time-waster games.

Also unlike consoles, phone manufacturers aren't very interested in investing in their device with stuff like exclusives, because no one is buying a phone based on the games on it.