Well, for one, there is a difference between using your pc for work or for your hobbies/free time. There are a lot of foss drivers for devices not officially supported on linux. However, since this is your job, you probably have no reason to rely on those when windows just works.

And about the windows-only software, some probably work on linux through wine. However, since this is what they make a living out of, they have no reason to even try that. Windows works for them, why waste time?

On my personal, non-job related pc, i have ran many windows-only apps or windows only peripherals when i made the switch. Overtime i need those less and less (either due to new alternatives or linux support being added).