*Yes, Wine is heavily developed by CodeWeavers, but CodeWeavers exists largely to help fund and support Wine.
Sounds like Microsoft just doesn't want to maintain 2 different versions so they're dumping it.
Also,
> Microsoft became the steward of the Mono Project when it acquired Xamarin in 2016
They probably never even wanted Mono, they just inherited it because they wanted Xamarin.... which they've also killed now according to https://dotnet.microsoft.com/en-us/apps/xamarin
If you build something new today in .NET land you are using a version that is compatible out of the box with linux, but there's gazillions of LOC .NET Framework out in enterprises that have yet not been migrated/rewritten.
But I don't actually know if Mono is stable enough to run Framework services on Linux?
I don't know how (if at all) Kudu is related to Mono, but on Azure you can run .NET Framework in e.g App Services (which uses Kudo under the hood). It's probably the only way to host a Framework service outside of IIS on a Windows VM. And Kudo contains references to Mono, and looks really linuxy when I've used it.
This is not a generally true statement, particularly with anything involving UI. WPF or anything modern WinForms are not supported. MAUI has no official Linux support.
Given the amount of whining about Linux GUI support despite good and proven solutions being provided, it leaves me with an impression some parts of Linux community actually don't want support at all and the goal is to have a convenient scapegoat to complain about.
Mono implements the GUI stuff like WinForms Microsoft .Net for Linux /cross platform has no GUI or maybe they added some new GUI now , I am not a .Net dev ,I know they were experimenting always with latest and greatest GUI stuff and failing to get traction.
Ideally few, but I think it is a good thing to have a separate implementation of the dotnet runtime as an insurance policy against the main contributor to dotnet.