

I wouldn’t call it an intentional restriction. Not trying to be a Steam apologist, but it would require extra work to make the controller use something other than Steam Input. Or to make a stand-alone Steam Input app. Not doing extra work is not what I would call a restriction. That’s like an Xbox controller not working on PlayStation because Microsoft didn’t put the extra work in to make it compatible. It’s not an intentional restriction. It’s just… extra work.
Ironically, both a PlayStation controller and Xbox controller work in Windows natively. But they don’t have all the fanciness of Steam Input. Steam Input is genuinely insane! I have a Steam Deck and the ways you can customize input are so finely detailed and powerful. They would have to make a standalone app to support all these features, or just give up and make a generic Xinput mode, which I don’t see the point of doing for such a powerful controller. It would be a waste. Just buy an Xbox controller.
I also don’t see it as a big deal to have to install Steam and register non-steam games in order to use the fancy Steam Controller. It’s free software, and you can configure it to start in your Library so you never even see any ads for games on sale. You just start your game, set up your controls perfectly, and you’re good to go. As a company having a near monopoly on PC gaming, Steam is pretty benevolent.

I should probably worry more that Firefox on my Steam Deck is basically logged into everything. If it were to be stolen…