Doesn't work. Try to do it without giving them a phone number or installing some other application. You can't. Or I couldn't.

how did you try? did you try registering a mozilla account?

You'll find out Mozilla has problems with sign in.

It's probably temporary, it doesn't have problems usually

And it presumes that I shouldn't be able to control my own browser.

they do it so that malware cant install unvetted addons to your browser. and if someone signs a malware addon this way, and some people report it, mozilla can disable it for everyone.

We need a new firefox - just like the original firefox showed that Mozilla was bloat and dumb, we need another that shows the current is bloat and dumb.

what you need is a footgun. you have it in about:config.