A lot of people like to play competitively with friends and strangers. The major free to play games with microtransaction models I think of are League of Legen

A lot of people like to play competitively with friends and strangers. The major free to play games with microtransaction models I think of are League of Legends, Hearthstone, and Dota 2 which feed off the competitive multiplayer aspects that single player games lack entirely. It often takes a bigger budget company to be able to support the servers and development hours needed to support big multiplayer games.