What is your experience based on?
I've been working with some large enterprises in the past (50k+ employees), all of them only use IE and all of them are full with some crappy ActiveX software, some by HP, some homegrown, it's really full of that crap. :( Even software that would support multi-platform is crippled in a way that only Windows+IE works, because in the projects noone cares if some other browser or (god forbid) another OS is supported.