[dessimus]

...implying that's a decision that IT makes of its own volition, and not because every other department has some one-off piece of software from 20 years ago that's no longer supported because the vendor is out of business but its still "Mission Critical".

[rcxdude]

There are a large number of IT departments that don't know how to manage anything else. (And a shocking number of windows-only ones that don't really know how to manage windows)