You are giving props to the Apple store (among others) for a couple of things here 1. Good Development Tools. 2. Handling payments. 3. Handling downloads. 4. A good OS.

So okay. Let's break this down a bit. Apple is a closed system. It provides a lot of the tools you reference because you literally cannot get those tools anywhere else and meet the standards required to publish anything to their store. I'm not sure if that's a good thing or a bad thing, but it is important context in comparing steam to Apple and their ecosystem.

I'm also not sure what debugging tools you'd expect to get from Valve in regards to Microsoft as a platform. You have to pay Microsoft for help because they're the ones with the source code and other system elements. Steam doesn't have control over those. The same goes for Apple. So for the record I don't know that this is relevant unless you're specially comparing their steam OS and what it should provide as a platform for designing games for steam OS and working within the steam ecosystem with that of other players like Microsoft, Apple, and Google.

Steam handles payments and even refunds.

Steam handles downloads.

My understanding and use case is that steam OS is pretty decent as far as gaming OS's are concerned and I haven't seen them catch a whole lot of flak for that. However I actually don't know and can't speak to this but would be happy to have you or others elaborate on the experience of developing for steam OS specially or just Linux. I'm sure it has its own set of pros and cons.

Followup question. Do you receive any of this stuff from Nintendo? Sony/PlayStation? They also take an 30% cut. They also have closed ecosystems as far as development. They also appear to handle payments, and downloads. I know that devkits have historically been exhorbitantly expensive but don't know what the barrier to entry is now or how that compares.