BIOS had to be replaced. It didn't have to be UEFI, but it did need to be something, even just a new 64-bit stage would have gone a long way. But nobody made such a thing, and the alternatives that actually exist like Coreboot do a lot less even than BIOS did. Past a certain point, pretending to be smol-bean 1980s/'90s hardware stops being a fun game and starts being a real limitation holding things back. Said "hardware abstraction layer" was getting to be more like a bunch of increasingly hard-to-maintain lies told to BIOS rather than a real service provided by BIOS.