That's what i'm saying, what you don't understand is that we often call rom chip that aren't romNo, it's not. If it is rewritable, it is not rom.
sometime it is a chip that is just software protected and the manifacturer call it rom
but it happen really often that we call a chip a rom while it isn't
so even if it is a bootROM it dosen't necesarlly mean that it is a rom or at least a true one (it could be blocked only via software while the hardware IS rewritable)
of course rom memory exist but it isn't because something is called a "ROM" that it is one