Libre office and Linux desktops are not line of business apps. They are platforms to run/supplement line of business apps. There are very few line of business apps that run HR, the finance department, EMR if you're in a hospital system, etc, etc, etc as open source or run on open source solutions. For decades Open Source advocates kept thinking it was the ability to run Office that shut down "The year of Linux desktops!!!" But that isn't it at all. It's those specialized apps that run the businesses that prevented it. I work in a hospital system, our line of business app is Epic or Cerner. Apps that digitize the health records. The requirements to run these apps is Windows Server, because that is what the front ends are built on. And these apps, especially the front ends, are heavy and complex. Any attempt to turn them into web apps has failed miserably because the performance just isn't there vs running say, the Epic/Cerner front end in a Citrix solution. Client-Server isn't dead, it just doesn't get sexy press anymore. Obviously if you work in web development, it is a very different story. But even in those shops, I'll bet the business support apps (HR, finance, etc) run heavily on Windows.
Lord knows I've tried to advocate for open source solutions where I can, but if the apps the business picks to suit their needs only runs in Windows? You're infrastructure has already been chosen for you. And THAT is what the average wannabe IT person on the internet doesn't understand in the slightest.