[brudgers]

or it is something else?

It is something elses: a decision not worth optimizing for first cost of hardware and the uncertainties of external support costs and a limited pool of qualified candidates for in-house support of desktop systems.

And of course the need to retrain employees who already know how to use commercial operating systems.

The arguments for desktop Linux in business are just arguments. There's not a strong business case in most cases. The people running companies are not any dumber than average. Good luck.