This is pretty similar to the policy at my company: you get a Mac, unless you specifically request a Linux laptop. If you need Windows for testing, Microsoft makes VM images available with a browser pre-installed at https://developer.microsoft.com/en-us/microsoft-edge/tools/v...
As a long time Windows user, it would take me a considerable amount of time to get used to the operating system and all applications and utilities that I need to be productive. Not saying Windows is great, but it works for me. And I'm pretty sure they don't hire people to learn an operating system.
With decent Linux knowledge I think being issued a MBP at my first job out of college was better for my productivity than a windows machine would have been within a week or so, even as a long time Windows user. Windows has generally always had a higher frequency of annoyances.