In addition, the company doesn’t invest in growing and retaining the rest of the development team for 20 years until said developer is near retirement, then finds that they need to hire 10 developers because 2 need to replace said person and 8 need to redo everything they did.

It’s been nearly 10 years since you needed to develop with C# on Windows.

New versions of .NET have been cross platform with a free IDE since 2016.