Earlier quoted context omitted.
What retraining? I have several clients, computer illiterate old ladies, who use Ubuntu and Debian just fine. No retraining required. They just jump on that desktop and go.
Until something goes wrong. Like if they can't read the tiny font in the file menu. Then they google it, and discover they need to "sudo apt-get install unity-tweak-tool." Then they manage to actually find a terminal window and run the command, and install the tool, and turn up every available font rendering option, and it still doesn't solve their problem. That is just one real world example. Linux is an operating s…
In my experience, the big problem in organizations are legacy documents and formats. Especially Excel. LibreOffice is good but it's not going to run the macros that were created 10 years ago by guys that are now retired in some beach.
The other big problem is specialized software (already amortized) that only run in Windows.
The funny thing is that kind of problems happens even between different versions of windows.