Question

I realize that enum cannot be used as a generic constraint, and Microsoft has declined to fix this bug.

Any reason why?

Answer 1

The link you posted says why:

and is a somewhat arbitrary limitation of the language

Potentially will change:

If we ever reopen constraints as a feature, this will be one of the things we will reevaluate. For the upcoming release we don’t have the opportunity to add any more language features, so you’ll see this resolved as “Won’t Fix”, but it remains on our lists for future consideration.