alt Hacker NewsIt was a big factor, but so were things like the way they treated their mobile browser for years and years, which is the platform 2/3 of browser traffic now originates.
According to statcounter's stats, Firefox never cracked 1% of monthly mobile traffic any month from when stats started in 2009. Even Opera and UC have more than double Firefox's average for the last year and they are just Chromium forks users are downloading off the stores.
For context, I recall that for years and years, Firefox was the highest ranked mobile browser. Mozilla invested a lot in mobile, Firefox devs had to rewrite the Android linker, invent new ways of starting binaries on Android, etc. just to make Firefox work (all of which were later used by Chrome for Android).
It still didn't make a dent in mobile browser shares.
Sure, Mozilla could have invested even more in Firefox mobile, but at some point, this would have come at the expense of Firefox desktop, which was the source of ~100% of the funding.