i do think that Steam has contributed to the overall devaluation of game prices via Steam Sale Culture, but i think the root of it really has to stem from the mobile market, which has "innovated" any number of insane consumerist practices for the games industry, chiefly the Rock Bottom Prices model and secondarily the Gacha model. those things got imported to the more traditional markets and Steam Sale Culture just happened to harmonize really well with those practices in general