Steam is market leader on downloadable PC games. Without steam you only do a fraction on digital sales on PC. The problem was that you had to ask Valve for permission and their review process is a mystery. When they say no - it meant no. No chance of reversal.
So Valve changed the way products enter steam and put the power into the hands of the community. YOU can now decide which game comes on steam. Well, most of the time.
Steam rejected an erotica game from Greenlight and then put a $100 fee on games which want to get published to hinder crap entering the system.
That still reminds me how console development works. You need some sort of control over content, otherwise your platform turns into a dirtpile.
That sex is not ok on steam but ultra violence is - that is an entirely American tragedy comedy.