I develop w/ Firefox and our tester tests with Chrome. I use our product quite a bit with an iPad. If problems are reported with Safari we fix them.

I've also worked at places where our product was specified to work with Chrome, I would try to run it with Firefox and no dice and they would not accept any ticket to fix bugs in Firefox.

There's an assumption today that browsers get updated frequently. My work computer is a managed Windows machine that I had administrator access to, the one complaint I have is that the Firefox is a long-term support version which is often long as in "in the tooth". Bloomberg would complain about it incessantly until I got the new LTS version. Other than that I think browsers are usually up to date.