I'll take your word for it I guess, but I don't see the logic. Why would my motherboard manufacturer be involved in this process?
edit: maximum downvotes for a legitimate question, thanks all
It's a chip that your motherboard manufacturer hardwired in (e.g. part of the chipset). Firmware updates need to go through the efi/bios they set up
The motherboard manufacturer integrated the chipset into their board. They worked with Intel, or Intel's spec/API directly. They are responsible for your machine's interaction with the CPU.
The same is true of all the devices directly integrated into your motherboard. Broadcom/Intel wireless chipset, Ethernet, audio, etc.