* A lot of software used by them is certainly Windows only (they will have to find alternatives, change their workflows or invest in some windows virtual machines)
* Windows tooling for organizations is much more mature. There's a reason virtually everyone uses AD.
* Linux is very focused on user freedoms. This is not usually important in the office. But freedom to configure things is a freedom to break thinks, and cause admin headache.
The problems are solvable, but it doesn't mean they don't exist.
Oh and I love nixos, and I always wonder how realistic would it be to use it in a company for management of thousands of desktop machines. Sounds like it would be perfect for it, but i don't know any stories.