I think this is a big fuck-up by Mozilla but I agree that some of the reactions are a bit over-emphatic. Actually I hope that this big backlash means that Mozilla is less likely than others to try something like that in the future. I personally don't plan on changing web browser and I hope Moz won't suffer too much for this mistake (if only because I love Rust).

That being said your reply and others before make me a tad uneasy because you seem to say that it's possible for a small team of, I guess, mostly marketing people can sneak an extension into a Firefox release "under the radar". Are you telling me that if I have some access to the Mozilla repos I can wait for one of this "bi-yearly" meetings and get questionable changes into the next release? A web browser is a critical piece of software, you shouldn't be able to push a novelty extension (regardless of intent) willy-nilly.

I think adding a new default extension in Firefox should go through tons of scrutiny and code review. And if that was the case I can't imagine that nobody would've raised a big red flag along the way saying "wait guys, are we sure we really want to do this?"