One thing I see as underestimated is that having a major standard device is huge for indie development and could greatly benefit the most flourishing artistic landscape.
One of the problems today is that the indie and AAA markets are increasingly distant, publishing a game on the PS5 or XSX digital store is prohibitive for a small indie team, but if Steam Machine is successful, we can expect more easy access to indie games by (ex)console gamers, and later a reduction in publishing costs on consoles.
I believe Steam Deck has already started this process, but with a device that will compete with the 9th generation of home consoles the indie game diffusion could accelerate.
I think the new device is good news. I can see what you’re saying - the benefit is if Steam Machines expand the PC games market with former console only players. But otherwise the threshold for PC development is already much lower than consoles; there are no dev kit fees, a wide choice of engines to target, relatively greater independence etc.
The steam machine may help somewhat in having a specific hardware profile to target, but the games are still on steam’s store so still have to be able to run widely on Windows or Linux. That’s always been the complexity of PC development - the steam machine doesn’t change that much. Although admittedly the Steam Verified benchmarks are useful for users to simplify understanding what their kit can actually run which will benefit indie devs.