First time around with the Steam Machines, like everyone else on planet earth, I had no interest in what I perceived as a pointless device. After getting my Steam Deck and abandoning gaming on a PC for any title that works well on the Deck, I’ve come to greatly value a console-like experience with my Steam Library. Being able to completely avoid the bullshit of Windows has become one of the most appealing aspects of my Deck, although prior to owning one, portability was the only major appeal.
At this point, I’d buy a new Steam Machine right away to be able to achieve that same console-like Steam experience but with more powerful hardware. Paired with the Deck for portability, that setup sounds like a dream come true.
I don’t think it has anything to do with the AMD GPU. It’s just software. If Valve controls both ends (client and host) it would work seemlessly with the Deck.