I just finished 30 years working for a municipality (Calgary) with about 12,000 desktops.
We were mixed DOS/Mac at first and when the IT department finally admitted that they were not toys, and that their beloved mainframe was dying at last, they took over PC IT from the departments, and immediately insisted on getting rid of Macs because of "one environment".
It was always about "support costs" and "total cost of ownership", a number they never actually had to calculate. They also never had to prove it was cheaper to do everything their way - but as a gross measure, our costs never went down. Not even on a per-PC basis.
We always had Unix, from when you had to have a workstation to run drafting software. Because IT clung to the mainframe to the bitter end, it was the engineering department Unix server room that took over running servers (this was happening around 1996, with the 1997 handover of Hong Kong to China imminent, when the joke was "will it actually be Hong Kong that takes over China" was big - in our shop, it really was a bunch of drafting-support staff that took over the server room!) We also ran all the E-mail servers on Solaris because 'e-mail' was "an Internet thing" and all corporate E-mail until then had been IBM PROFS. Finally a few Windows servers were allowed to provide Outlook, but only after Windows 2000 Server got decent. Everything else is still Unix.
Unix support staff were NOT hard to find for a large server room. Windows server staff that could support a LARGE installation were rarer! MS courses turn out lots of guys that can run a dentist's office but very few that can run a city.
After all support went to IT...there was no actual support, except re-installs. They re-install the software, they re-install your whole machine, but they. will. NOT. come to your machine and help you with your difficult spreadsheet. None of the alleged "support" staff understand any of our software except for basic MS-Office apps they themselves have to use (and, as mentioned, the won't come help with that, either). But for any special office software of the type that the article speaks of, departments have to drum up their own local "power users" for support, who by the way are discouraged from it by IT and certainly given no passwords or special access.
And for that matter, what does the client even matter to IT? They hate clients. All business software that can possibly be moved to web apps for easier admin, has been. It would run on Android just as well.
So I just don't see what the big deal is. Here's an experiment: Offer, gasp TWO alternatives with internal costs that match the actual support costs of each choice, then let your customers choose which desktop they want.