Comment by nrclark

It matters when you're doing custom hardware, or when you're designing a product where boot speed matters, or when you need to implement something special.

A full-featured U-Boot implementation would be fine IMO. But for the generations that I've used, that's not on the table. What we get is a proprietary flow through a proprietary hypervisor into a fork of Android's bootloader (even if vanilla Linux is the target OS). There's no way to control startup boot options, and no way to use KVM, Xen or any hypervisor except the proprietary one that's also part of the boot chain.

This doesn't lend itself to flexible products, or to products that are easy for a company to design or support. That is why things like this happen: https://news.ycombinator.com/item?id=46008156