How walled is it really though, it's literally just a linux PC. SteamOS is the (arch-based) distro, and Valve is just a system integrator selling what are effectively pre built systems. Steam Machines are meant to have competitors selling their own systems with their own hardware choices.

This is no different than buying a gaming PC from Cyberpower, Alienware, Asus, etc except that the OS wouldn't be windows.

Of course, as it stands there are no other competitors but that's just because we're in uncharted territory. If the steam machine sells well, then other integrators will make their own versions (like we saw with the Lenovo Legion & ROG Ally).

The idea that this is a "walled garden" when you can install any software you want, swap the OS, install cracked games, etc. is ridiculous. This kind of thinking is exactly why people think there's too much infighting in the Linux community. Everyone talks about how they want Linux to become more mainstream and to dethrone windows. But when something like this comes around to actually do that, you all complain about how awful it is