I can confirm this, everyone I knew at the time was coding on Firefox even if no-one required any compatibility with it just for that reason, it was just much easier to code with.

When I shared my observations with coworkers, they would nod and say they had experienced the same thing. Same with peers I knew outside of work. Either we were in a very large bubble, or that was happening everywhere. And I think the rise of Mozilla aligns with those observations. It 'just worked' because everyone quietly made sure it did, even when people told them not to.

And yet, the decision to target a specific browser is STILL a business decision.