I think mozilla is really useful to google, obviously for monopoly reasons but here is a rather petty mundane example. Reading through a bunch of the TC39 minutes (W3C JS standards body), all of the major browsers including Moz have reps, and the Google ones tend to dominate the conversation and can tend to block proposals and generally be vocal about where the rubber meets the road. The google reps also seem to think they can speak for Mozilla saying things to the effect of I don’t think Moz will be on board with that, that won’t work for them. So they get more power behind the scenes through their patronage.

Incidentally, Microsoft uses Github votes the same way, except they outright own then instead of just controlling 98% of their funding.

In other words, Firefox might be around longer than looks reasonable from a distance.