How many of you don't understand that 30 procent is/was the standart like google play or the app store they usually charged 30 procent and guess what steam runs on pcs or something pc like which means that other gaming stores can be run on them, but people usually don't because well they are enshitified. Steam also provides services to game developers like matchmaking, cloud saves, p2p connections and everything else that's in steamworks.