To me this is the ultimate failing of ARM as an ISA, the fact that you even need to consider "targeting" allows a deficient ISA like x86 to still stand head and shoulders above it in terms of OEM support (though perhaps not security)

It has nothing to do with the ISA and everything to do with the system architecture. Look up PC-98.

Also: PC being a "standard" is a lie; ACPI is a horror.