Yeah that's true. But I suppose you could just as well buy any other windows/linux PC. (I did so after finally ditching the playing-games-in-bootcamp-on-an-imac life.) I realize the same could be said about the "a box under the living room tv" use case, but I feel like to a lesser degree?
My main issue is that I don't want or have space for a massive PC tower. And building a small form factor PC is both very expensive and very difficult.
All the components come at a premium price and you also get to spend hours finding obscure forums with exact measurements of cases and components to see if the GPU fits lengthwise or whether a specific CPU + cooler is too tall for the case =)
And even if you make it, you're easily way over 1k€ before get to even picking the M.2 drive and RAM.
Thus: Steam Machine. I click "buy" on Steam, it appears on my doorstep, I plug it in and it'll start working.
I have an M1 Macbook, no gaming for me. So the Steam Machine is perfect for me.
I can just tap a button, it'll turn on and I can be gaming on my main monitor before I have time to grab a controller.