That sounds like the same class of argument as "all an operating system needs to provide is process scheduling and hardware access". It doesn't match user expectations and it certainly isn't a good user experience. Having to sign into a different account for every game to get basic functionality is a nightmare. Users want to purchase a game from a store, install it, play it, and have everything work. That's it - no other configuration or connections required.
The answer to that isn't putting all stores but one out of business, it's having a single-sign-on provider.
Also, I doubt you would criticize an embedded OS for only having process scheduling and hardware access, because that's probably all it was designed to do. Similarly, a low-cost store may want to skip on providing all those extra features so they can keep prices down.
