Valve literally hosts petabytes of game data and allows any user to download them at any time. That's not nothing, data storage is

No, it's really not. Azure and AWS storage is dirt cheap, especially if it's cold storage and you can have a second or two delay when retrieving the file. If it was expensive, they wouldn't be the most profitable tech company per employee.

Steam has so many backend features that allow devs to skip so many networking steps that can otherwise be a huge nightmare.

No, it doesn't. It provides a small handful of APIs around friends and matchmaking, which Xbox and Epic also provide for half the fees, in addition to the generic Azure and AWS versions.

Not sure why you think they are literally just a webpage that has a purchase button next to a game.

I'm a software engineer whos built both an app store and 3d rendering engines. I know exactly how little work it took Valve to build Steam and how much work it took Epic to build Unreal.

They are not remotely comparable. Gamers are just lemmings who love Valve cause everyone loves Valve and talks about Valve, when in reality Valve has overcharged and ripped them off for decades.