The platform, which is overwhelmed by “trash” titles (in 2017 Steam released more than 7,600 games ), is no longer attracted to major publishers, and since the last year we have been watching an interesting trend. Games of big publishers are leaving Steam. After EA, big titles from Activision and Bethesda will be released on their own platform and we can roughly calculate, how much Steam loses. Discord, with larger audience than Steam, is launching their own store too.
Source: N4G PC 2018 – The beginning of Steam's end as a leader on the PC platform