I agree outputs can be muted before shutdown, saved as a scene or not, but what I have in mind is a shared use between several people (or a hurry guy like me…), where you don’t know what was the setting the previous user left in the mixer.
I also agree that levels can be lowered on the FOH itself, but I think starting with everything muted could be more convenient.
Maybe not as an option that may be overwritten by the previous user, but as a trick like holding down one the buttons when powering on.