Apple also takes 30% (or did it change to 15%? Definitely used to, tho). So does Google, Amazon app store, Samsung Galaxy store (just to name some in the mobile industry). And guess ehat, even GOG takes 30%.

I would argue that, compared to other services that also take 30%, and taking them as a baseline for what they offer on top of “buy download play” model, Steam is still very generous as it offers cloud saves, achievements, workshop, community forum, chat, streaming, offline mode, and tons of little stuff that make your life easier.