In Fallout 76’s beta FAQ, it’s stated that “the game will be available on Xbox One, PlayStation 4, and on PC (via Bethesda.net only)." The lack of Steam support has since been confirmed by Bethesda, which said “the PC version of Fallout 76, for both the B.E.T.A. and the launch, will be available only via Bethesda.net, not on Steam."
Bethesda.net has seen PC titles launch exclusively on the platform in the past—Fallout Shelter and Quake Champions—both of which eventually arrived on Steam. While these instances could suggest that Fallout 76 will come to Valve’s service in time, Bethesda never indicated that this would happen.
Bethesda didn't specify any reasons for choosing its own product over Steam but, as with so many things in life, it could all come down to money. Steam charges publishers a 30 percent fee every time a game is sold on its platform; as Fallout 76 will likely be popular, that translates to a lot of money lost to Valve. Plus, the exclusivity should help increase the number of visitors to Bethesda.net.
The news does come as a bit of a surprise, considering that Steam is the world’s largest digital games distribution service and used by millions. But the announcement comes just after Epic Games confirmed that Fortnite would be avoiding Google Play’s 30 percent fee by letting Android users download it straight from the mobile website.