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.

Only on games sold through Steam itself. Unlike any other store out there they don't charge for keys sold somewhere else, so in practice that 30% is significantly lower if you put in any effort to sell your games elsewhere too. This is why publishers like Paradox have their own store and heavily promote it, they just sell Steam keys there without having to pay the 30%.