I'd be interested to hear what it was like on the dev team. I'm sure they don't super care about throwing elbows at Firefox now that that fight is won, so maybe the issues are just holdover from past decisions.

But 10 years ago... was it just "don't test on firefox"?

Or "heeey, we just made a brand new feature [that no one else uses] go ahead and use it in mail and maps!"

Or more openly nefarious?