Right. Windows support is a feature outside of the scope of Linux package managers. If they weren't tethered to specific distros I don't see why one couldn't support multiple platforms. It hasn't historically, but Windows has a bunch of package managers, even one supported by Microsoft.

I think "largest" is quite an exaggeration since historically scripting languages packaging has been rather terrible on Windows. While Windows was a consideration for languages like Python (I've read they avoided Make because of Windows), for me cygwin always coming up along with it until recently.