The "use an inferior tool for philosophical reasons" mindset is already pretty unconvincing for me. A chromium fork maintained by a pro-user, pro-privacy team is the best of both worlds and doesn't expose you to Mozilla's fad-chasing.
These assumptions would be true of a for-profit entity like Google, Apple, Microsoft, but it's not as directly applicable to Mozilla.
Mozilla exists as it does today entirely due to Google's largess.