When did warnings indicating that "this option will destroy your computer if set carelessly" become verboten? Why waste the expensive time of advanced users for no real benefit to the masses?
It might be good for you to remember that those "masses" are just people with other things to do with their lives - they're doctors, lawyers, concert violinists, nuclear physicists, biologists, teachers, ... and they just want their damned browser to work without having to mess around, and preferably not break with cryptic error messages they don't care about, because, frankly, they have better things to do.
It's only the advanced users who are willing go through this path because they want to tweak a settings. And the question would be, is it really worth making such an impractical tool out of about:config and thus wasting time of advanced users when it was designed for their own use, for the sake of keeping non-advanced users out this setting panel.