Why? Not even Mozilla had faith in Firefox OS, and on a phone like this, it's barely powerful enough to. I'm not trying to attack you, I'm just genuinely confused at this viewpoint.
None of my below rants are directed at you personally!
FF OS lives on today as KaiOS and is extremely popular in the devloping world where even an Android Go device requires far too much hardware specs for the price a given set of locals want or can afford to pay.
If you look at some of the devices that run it like the JioPhone, you can see that it sits quite comfortably in the space formerly occupied by the BREW systems of the world, but has little touches like email sending, Google Assistant, etc.
Edit: just to give some scale to the Android Go bloat (let alone plain old Android), the HTC Desire Z (https://en.wikipedia.org/wiki/HTC_Desire_Z) has 512 MB of RAM and a paltry processor, not powerful even for its day.
That device ran the current set of Android OSes at the time, and if modded today, can even be made to run Android KitKat, where official support stopped at Android Gingerbread. Today, that device is barely considered Android Go compatible, mostly due to its CPU and storage limitations.
In 2010, we took pictures, checked emails, played games, browsed the mobile web, performed calls, texts, IMs, watched videos, streamed music, and drove/bussed/walked with navigation.
Today...we do much the same things, but in a 'once more, with ~~feeling~~ AI` manner. There are very few totally new things compared to 2010, we just let mobile apps bloat up to web development-level bloat.
In my cynical moments, I look at the processing power eaten on my OS, wasted on wakelocks and ads and think to myself that somewhere, Ralphie is in the ~~Magic School Bus~~ cell phone factory and spinning dials saying 'more RAM, more CPU, more network speed, I don't know what to do, the software is all slow!' because every time he ups a spec, the bloat absorbs it without reducing user latency one bit.
512MB is not even enough (on its own) to run a user-friendly Linux desktop these days - you'll need to setup some swap to make it workable. And that's without even launching a web browser, just light native apps. ISTM that the bloat is impacting way more than just mobile.
Mozilla did not want to maintain XUL or Fennec (which was hard to develop for, jumping between layers in C++ & javascript), but Qualcomm, Facebook, Google & the bevy of manufacturers and carriers that Mozilla had rallied behind FirefoxOS forked it and continued carrying on...
