It also really helps that Firefox never deletes cookies by default and never tells you about this. We 'respect' your privacy, yes, we do! Really! Look, you will have only one google cookie when you start a very new firefox.
We really respect your privacy, yes! We will reiterate that until you believe it, but never change our privacy destroying default settings, because we 'respect' you!
It "works for me" and it'd probably work for a lot of (perhaps even most) other users so maybe it would be an acceptable default. I don't know.
I think there's a happy medium somewhere between these two extremes that absolutely would be an acceptable default, though. Firefox could certainly come with better defaults if Mozilla truly valued privacy that high.
(FWIW, my mozilla.cfg -- pointed to by general.config.filename -- currently has 127 settings in it. It's been added to over the years, though, so some of those are certainly deprecated by now.)