Pfft, who would do that? As a Firefox user myself I never would. Carve out a bit of time on the down-low to enhance cross-browser support on a website after management shortsightedly told me to just block anything other than Chrome? No no no! Not me!
Of course as others here (including you) have pointed out, it’s much less of an issue these days. Though it does still happen, it’s nowhere near as bad as the IE days (that browser can burn in hell for all eternity!).