It’s a little easier when the machine is dedicated to that and only that. The OS doesn’t have all this extra crap running in the background that takes resources from the game because it was designed for that in mind.

That and devs have just one machine to design their game for versus trying to make their game run on hundreds of machines with very different specs.

Some devs, especially first party devs who work closely with or directly for the manufacturer also have insider knowledge of the system they’re developing the game for. Some developers did this in the Nintendo 64 era by tapping into resources that other games weren’t using to push out even more performance from the hardware.

I doubt windows either has or wants to have that functionality, given their more business/general purpose oriented focus, also the steam deck runs on Linux.

A part of me wonders if it would be possible to put the Linux distro/is of a steam deck onto a dedicated gaming computer to get some of the optimisations from it like that.