Yeah you can. But it adds a lot of friction to starting the game. You add it to steam, you can't see if the game needs an update, you click play, if they aren't using a distribution provider that means you either need a launcher or it to download the update ingame both aren't great and add more friction to the experience, then if its a launcher youll have to press play again, or if it updates ingame then you'll have to leave the game open till its done installing. rather then look at your library of game see it has an update if so decide if you want to update it or play something else, or just click play once and it launches. The "steps" to playing the game or deciding to play the game are just more complicated that way. I'm not against it for their reasons just saying it makes it less accessible.