It’s important because it allows them to directly modify the CPU’s microcode. Basically, the CPU has its own set of instructions, called microcode, which controls how the chip functions on a physical level. If they manage to change your microcode, even a full system reformat won’t kill the virus; You’ll need to either re-flash the CPU (which is not something the standard user or even power user will know how to do) or replace the entire CPU.
It’s important because it allows them to directly modify the CPU’s microcode. Basically, the CPU has its own set of instructions, called microcode, which controls how the chip functions on a physical level. If they manage to change your microcode, even a full system reformat won’t kill the virus; You’ll need to either re-flash the CPU (which is not something the standard user or even power user will know how to do) or replace the entire CPU.