Yes, Mono is used by Wine to support Windows .NET applications since it’s a) open source and b) contains support for Windows Forms and other Windows-only APIs.
They can’t ship the regular .NET framework by default for licensing reasons but it can be installed with winetricks to replace Mono, which is sometimes necessary for compatibility reasons.
Does Mono have any purpose any longer? What is the point now that dotnet core is so well-established?
Yes, Mono is used by Wine to support Windows .NET applications since it’s a) open source and b) contains support for Windows Forms and other Windows-only APIs.
They can’t ship the regular .NET framework by default for licensing reasons but it can be installed with winetricks to replace Mono, which is sometimes necessary for compatibility reasons.