Thus they barely get their stuff working on the major commercial platforms, and all the rest have to either beg for specs so they can write their own (good luck) or reverse engineers (and risking bricking the hardware because of abusing standards for firmware flashing and whatsnot).
And your primary complaint boils down to power management, aka ACPI. And it, like UEFI, suffers from the second system effect (Linus Torvalds do not hold either in high regard for example). There is at least one documented case of a name brand motherboard offering up junk ACPI data unless Linux claimed to be Windows.
Linux appears to be at a standstill because each time a new motherboard or expansion card gets released, the process basically starts from ground zero unless it happens to be based of some bottom of the barrel chip with zero modifications so the Linux devs can just add another product ID to the driver table and call it a day (resulting in things like USB webcam drivers that support some 100+ camera models).