Comment by jeroenhd

BIOS didn't have a spec at all, it was hacks stapled to reverse-engineered chips that were Good Enough To Ship for IBM decades ago.

Most of the alternatives require brand+model specific kernels and boot mechanisms, at least UEFI has a standard. I dream of the day smartphones run UEFI instead of the weird factory bootloader + custom uBoot mess that we're in right now.