With Facebook code intruding into every nook and cranny of the web via React and Google's position as digital Sauron, monitoring and parsing out your search history, watch history, all phone activity, emails, SMSes, and more, user identity resellers are a formidable foe, and Mozilla is in its familiar position as the David of noble, non-moneyed interests challenging the user-hostile Goliath.
Firefox may find unlikely allies in Microsoft and Apple, since these two companies still make at least some money selling an actual product instead of just slurping up information about their users and repackaging it. The best thing Mozilla could do is convince Apple and Microsoft to give up their independent lackluster browser implementations and ship Firefox as the default instead.