In swear this mainly has to do with it's about:config being so much more robust and vast than chromium's //flags settings. The fact so many privacy related forks (Librewolf, Mullvad, Mull, Tor) are based off of firefox and not chromium (Ungoogled Chromium) should point to why these corporations are seething at it.

Google was/is keeping Firefox afloat via funding as the article points out. This is mainly due to the fact that Google didn't have a real competitor in the browser space for some time until Microsoft got Edge off the ground and finally killed Internet Explorer.

Personally I see Firefox as being the superior browser for privacy and customization. I also don't think it's going anywhere, but it's funding relying so heavily on one entity is an issue. If Google decides to pull it's funding of Firefox and no other major corporation steps in to provide the needed cash flow... well who knows, guess it'll be a chromium world after all.