You bring up a lot of good points, but something I would to add is that there is a reason why you wouldn't want it to act like a standard xinput device without steam.

One big usecase for the steam controller is as the primary (and possibly only) input for a HTPC (such as the steam machine). So having the controller act as a basic keyboard and mouse without steam (ie: lizard mode) allows you to navigate menus that a standard controller can't such as pre-boot Operating System menus or BIOS menus without having to breakout a keyboard and mouse.

I think you are describing just one category of a way to stream, when you talk about connecting your controller to your phone, and then the phone acts as a wireless middleman to your PC.

You... can just directly, wirelessly, connect a controller to a PC via a 2.4ghz dongles, usb dongles, bluetooth connections... many ways to do this exist. The Steam Controller uses a usb dongle (which also doubles as a wireless charger for the controller when physically connected), and it also works via bluetooth (iirc).

Streaming is not the same thing as connecting a controller, not necessarily. You can stream the game rendering output from your PC to a TV, or to a phone, or to another PC... and you could do that over a local network, or you could do that from like a server farm across the internet, to a local device that doesn't have to involve the controller, at all.

Like when you are watching a livestream ... thats likely a phone camera or usb camera, streaming, live, to your device.

There are many different protocols and standards for streaming different kinds of content, to and from different kinds of hardware, via differing physical transmission methods, which may or may not support various kinds of input/output as well. Some of these are proprietary, some are open source, some work on some operating systems, specific hardware architecture (x86 vs ARM)... etc.

I do hear what you are saying when a proprietary tech is involved anywhere in the loop. Yes, it is always possible that one day, that could blow up in your face.

However, as best I am aware, SteamInput is a totally open standard... its sort of like a game engine where the source code is 'available', but it isn't fully open to be freely modifiable.

You bring up robotics. You can make a robotics controller program in Godot, I've seen people do it. Godot also has an opensource plugin that supports SteamInput. So you could make a robotics project that works with a Steam Controller in that way. I'd say its pretty likely there are other game engines that support Steam Input as well, or other projects that do this in their own way.

But yes, it is always possible that Steam could become evil when Gabe retires/dies.

However, just as others have noted that proprietary designed Nintendo controllers have had people develop software for them that enables them to work on non Nintendo products... I would be amazed if that is not basically the case for the Steam Controller within a year or two, if it isn't functionally already the case via stuff that's been developed for the Steam Deck, that would only need updates.

Why does Valve not use a totally open universal standard?

Because no existing totally open universal standards supports all of the input and control functionality that the SteamInput system does.

Steam has a whole system of controller configs, hosted on Steam: A game publisher can issue an 'official controller template' for their games on Steam. Through Steam, users can tweak and customize and rebind keys and buttons and commands, and create their own controller templates for games... you can save these locally, tie them to your Steam account so they'll work across devices, sort of like cloud saves, or, you can even publically upload these controller templates so that other users can use them, and then they can modify them, make their own version, etc.

Would all of this ideally be totally open source?

Yes.

But... Valve had to invent all of this, so they based it off of what they already had, that encourages people to use it with their platform, which is at least currently, a very open and featureful platform, at least as far as platforms go.

They are, after all, in a platform/console war, with other corpos, where said other corpos all have publically traded stocks and thus more money snd also investors they must please, whereas Valve does not.

Valve is not a third party, universal peripheral manufacturer.

They are a first party peripheral manufacturer.

Hopefully this reads less as an 'I think this is totslly morally correct' defense, than it does as an explanation.

Other companies do the exact same though, Nintendo controllers don't support non-Nintendo devices (although they've been reverse-engineered for Steam and Linux).

But these lemmings on the internet don't like it if you criticise Lord Gaben.

Other companies do do this.... and people are fine with it,. Get a grip.