Quoting: RandomizedKirbyTree47

Display I imagine is the only one that would actually be relaxed, since we're talking about all sorts of resolutions since the Steam Machine is just a mini PC with SteamOS Linux on it. Input, Seamlessness and System Support cannot be relaxed in any way or the whole system would be a bit pointless.

Why?

The Steam Machine is a desktop computer. Why does it need full controller support? Why does it require an on-screen keyboard? Why do launchers need to be navigable with a controller?

Those make sense for Steam Deck because it's a handheld console with a built-in controller, and is not expected to be used with a mouse or keyboard. But for an ordinary desktop computer, which the Steam Machine is, all those conditions can be dropped.

Putting it plainly, you can plug a PC to a TV since forever, and all PC games are playable on a typical PC setup (monitor+kbd+mouse on a desk)... but a TV usually means a couch or bed instead of a desk and kbd+mouse doesn't really work on a couch or bed.

If the Steam Machine is meant to compete with consoles, then it's essential that Valve pressures for controller support in its games catalog to improve.