More specifically: they chose Firebox
because it doesn't have those kind of features. If the just wanted a (sorta-kinda) open-source browser filled with all the latest hype features they would've simply used Chromium.
Using Firefox is a political choice. People use it because it's one of the few remaining traditional browsers which isn't a tentacle of Big Tech. Chasing the competition and adding the stuff your users are actively trying to avoid isn't going to work.
