That's an argument for Steam not being the only game store, it doesn't make much sense after you already bought it from Steam and the game requires an alternate launcher to be installed.

But on that other matter, I think you have a point in theory, but EA, Ubisoft and Activision Blizzard don't seem to have any interest in providing a better service or unique benefits. Steam's dominance is overly maligned when it's the only one where the company actually earned its place, by providing a better service.

And even then Steam doesn't even have as much of a monopoly over PC games as console manufacturers actually do over each of their platforms. But since it is by design that consoles only support the platform-maker approved games, it doesn't even register in people's minds as a monopoly. As if they were never supposed to control these devices they have bought.