That's great that microsoft calls it that, but that doesn't really matter.
Winget is just as much a package manager, as the "add or uninstall apps" tab in windows settings is.
It's just a interface. But the actual act of installing is done by different program.
Microsoft literally calls it along with some complementary services the "Windows Package Manager"
>Package manager role is, well, managing packages.
Which is what it refers to what it is managing.
>but dependency managing and installation it self is handled by the installers
The package manifest is allows for dependencies on other packages.