At best, it means sysadmin have to support both Linux and windows. You’re going to double everyone’s tools.
This reads like an engineer who is way too invested in using their toolset and thinks everyone else is stupid for not using the same. Like someone who has never worked in management or had to make business decisions. They are looking at it only through a tech viewpoint.
Not only would you need to have an IT team that knew how to manage and support it (which costs money and time) but you then have to train your entire work force which costs insane amounts of time. You would have to do IT training for every new hire for them to even use their computer. That sort of time and training (which takes two employees, the trainer and trainee) costs a lot of money, far more than any OS licensing or end user software costs. Plus the decreased work output while the user to get used to the toolset.
In a software development company, sure, Linux might be a valid option. But it’s not ready for most companies main workforce. And it’s not a technological issue. It’s a human resources issue.