Oh and before anyone says anything, I'm a staunch Firefox user and have been continuously since its first release. And in the last few years I'm starting to see

Oh and before anyone says anything, I'm a staunch Firefox user and have been continuously since its first release. And in the last few years I'm starting to see a marked growth in sites which don't work in Firefox, usually because of something like a bug in their Content Security Policy which Firefox correctly rejects and Chrome doesn't. It's becoming increasingly clear that the vast majority of web developers are now exclusively using Chrome and resent the idea of testing elsewhere.