Unfortunately, logic and sanity fall apart when you talk to hardcore Linux users and they get on their tirade about FREEDOM!!!! Check out absolutely any systemd thread for more evidence.
Freedom has a high cost - attention, maintenance, and constant vigilance. This is something we are learning all too well in this current political climate in the US. It's something Open Source maintainers are learning as they climb in years and experience and their time becomes more and more precious.
We used to tell people like these folk "Patches welcome," but then we learned that they give us those patches... and literally never maintain any aspect of them, so now we're stuck supporting their useless, broken, out of date features for years on end.
Worse, some of them come with baked in security vulnerabilities, and still get left on by default because next to nobody knows what it actually does. But we sure as hell get yelled at when we try to remove those broken features - it becomes an uphill battle, every time. We've seen it for Linux device drivers for super obscure hardware, we've seen it for features in desktop applications and entire desktop environments, we're seeing it again in web browsers.
If you aren't using PulseAudio, you have fully accepted that you are willing to be on the fringe Mozilla made the right call. Freedom has a price.
[1]: by measure of software that I maintain on Linux - last I checked less than 100 installs reporting usage information use the non-Pulse backend, albeit I accept those same folk are likely the folk that would disable usage reporting, so we can never know with absolute certainty. I can't imagine Mozilla's numbers are greatly different than what I'm seeing.