As pointed out this isn't what happens, but even if vendors did ship Coreboot it'd have the same behaviour (because that's what the vendors want) and you still wouldn't be able to reflash it because they'd still be using Boot Guard. Coreboot isn't some magical freedom enhancing technology that can be sprinkled on a platform to make it respect its users, in the same way that the use of Linux in Android doesn't guarantee any strong user benefits over the iOS kernel.

I think the implication was pretty clear that coreboot plus the ability to reflash your firmware is necessary.

I think you misunderstood. It doesn't affect the speed. The BIOS still boots as fast, but the logo stays up while other things happen.

Ah, I see. Regardless, coreboot is still important for other reasons.

As the other reply in this thread pointed out, this doesn't mean that the BIOS takes longer to boot, it means that the logo keeps showing as the OS boots.

(I would still love to see more open BIOSes, though.)