That would seem to be price fixing by its very definition. (EDIT: Note that I’m not making any judgment on this class action. The reality of pricing on IsThereAnyDeal would suggest that there is no such rule that prices can’t be lower outside of Steam.)
https://en.wikipedia.org/wiki/Price_fixing
manufacturers and retailers may conspire to sell at a common “retail” price; set a common minimum sales price, where sellers agree not to discount the sales price below the agreed-to minimum price
And the question is irrelevant. Other companies can still benefit from external price fixing.
From the actual lawsuit documents (emphasis is mine):
EDIT: Uh… Exactly what part are we downvoting here? All I did was quote the lawsuit.