This might just be one of those cases. Why would Microsoft want to invest in another distribution platform when they already have the Microsoft Store where they can do whatever they want?
Sure, WinGet has an MIT license, but that doesn't mean anything. The only important thing is who gets to commit to the manifest(s) on the master branch. That's Microsoft. They own it. They control it. They curate it. They decide who gets to distribute via it.
I'd bet money they'll tie it in to Azure somehow at some point.
Having a widely accepted and used package format would solve that. You could just pick the package for notepad++ and others and push them to workstations via Intune.