No, just an intermediate kernel is written into flash memory along with coreboot. It doesn't wear little flash chip as it doesn't write anything which needs to persist, that's actually one of the points of this solution. Its sole role is to chain-load your destination kernel. So you just basically move your bootloader into non trivially writable memory (as it can be write-locked) to make it more tamper proof.
There is always a risk of bricking your system if you're not careful, but wearing off flash isn't one of those risks if that's the concern.