Everything slightly right and mostly wrong with exclusive titles on different gaming platforms. Let me preface this by stating, I’m specifically giving my thoughts from the prospective of a costumer. I have no idea how some of the financial numbers shakeout. So I’m not even going to try and pretend that I know or even understand the behind the scenes between these gaming platforms(otherwise known as game launchers) and the game developers.
Steam has been the tried and true for all PC gamers for the past few decades now. Competitors tried their hand, arguably unsuccessfully. EA came through with it’s Origin platform, Ubisoft with UPlay, Blizzard with Battle.net, Bethesda … You get the idea. The only useful ones for the longest time was Steam for it’s vast selection and simplistic features, and GOG Galaxy for it’s strict no DRM policy. During the early 2000’s DRM was kind of a big deal, but a lot of advancements have been made to not act as an inconvenience.
Blizzard decided to produce their own launcher with Battle.net to house World of Warcraft, Starcraft, Diablo, etc. This might be the only launcher outside of Steam I can make any sense of.