The point is that OP expected hardened Firefox to be included by default, and then expected a warning in the documentation to explain that the default version is in fact not hardened.
And don’t get me wrong, I’m an advocate for hardening everything, but on my machine since I know everyone’s needs are going to be different. And there are ways to easily and reliably harden Firefox: [Guide] Automatically install extensions and configure new (dispvm) hardened Firefox profiles with arkenfox user.js and policies
At the end of the day it just comes down to common sense. It can’t be expected that everyone will be satisfied with the default settings, but a project being open-source generally means it’s quite trivial to customize it to one’s demands.