as days pass by

A few days ago I noted that an Acorn Electron booted from ROM which was fast, and that someone seemed to have rediscovered the technique. Is there any reason why someone couldn’t build a computer with Linux in ROM rather than on disc, so it booted really really quickly? You’d need some kind of flash memory thing so you could update it with new kernels or something, I accept, but would it work? I don’t know enough about the kernel and surrounding low-level OS stuff to know whether too much of it needs to be writable while it’s working.