You're right, although you'd probably find that in many shops developers have the latitude to use Firefox off their own initiative if they so chose.
I recently finished a 7 year stint at a company where I was CTO. I always made it clear that we needed to be testing functionality in more than just Chrome because, apart from anything else, a good chunk of our users would be on mobile, and many of those on iOS (i.e., using Safari). I used Firefox as my main browser for probably 4 - 5 of those 7 years, and I suggested engineers do the same because it tends to hew closer to web standards than Chrome does (meaning that if it works in Firefox it'll almost certainly work in Chrome, but the reverse doesn't necessarily hold). That gradually bled through the development team, with a number of the engineers using Firefox as their main browser. That's really all it needs is a few people using it for their day to day work.
I made the change on principle because I could see the way the wind was blowing and - even then - Google were doing plenty of things I didn't like. I like to think that influenced the team as well but, reality check, they probably did it to avoid me moaning at them about bugs running in Firefox all the time.