I dunno, there is a bunch of motherboard/RAM/CPU combinations that don't work properly together. Just because the socket is right, doesn't mean the component supports it.
Slightly recent example is newly launched CPU architectures using contemporary sockets, where you have to insert a supported CPU first, update BIOS and only then could the motherboard support newly launched CPU. But if you just have the one, new CPU, it might not be able to boot.
That's fair as well.. matching launch chipset and CPU is a pain. Also, even in Phoenix, I had trouble getting access to an older CPU to update a MB chipset for a new build last year... wound up spending $100 more on a newer chipset MB. It had bios flashback, but that didn't work.
Slightly recent example is newly launched CPU architectures using contemporary sockets, where you have to insert a supported CPU first, update BIOS and only then could the motherboard support newly launched CPU. But if you just have the one, new CPU, it might not be able to boot.