> Its an unfortunate system because steam isn't actually providing that much value

I have to heavily disagree with that.

Other than as you mentioned, the huge amount of eyeballs on all of their library content which you just won't get anywhere near close to. Along with people already having credit on their steam account so they can instantly buy a product without entering payment info.

There's also the distribution and update mechanisms which are such a huge win for the customer as well as developers.

I can also guarantee you, if Steam didn't exist, there would be other 'central store/repo's' that would absolutely be trying to enter this space. Providing an easy location for gamers looking to find new content. It's a win/win/win for all of Valve, Developers & Customers.