It would still be significantly better if mobos ran coreboot (or some open source firmware) with some binary blobs for WiFi/Bluetooth. It's not out of the ordin

It would still be significantly better if mobos ran coreboot (or some open source firmware) with some binary blobs for WiFi/Bluetooth. It's not out of the ordinary to have this arrangement; the newer Nvidia GPUs support open source kernel modules because they use encrypted binary blobs to lock down actual functionality. The WiFi/Bluetooth chips could even have open source firmware but require a signed hash of that firmware binary.