Good question, but the answer still NO, As WinRT in fact is not like .NET, but it's a whole new API, Windows OS prior Windows 10, used to have a Win32 API, but now they made a new API named WinRT. Soon or later the entire Win32 API will be deprecated.
And as you may know WinRT being an API means it's deeply integrated into the system. it's not just some top layer framework like .NET.
You can read more about the difference between WinRT (at Windows 8.1) and UWP (at Windows 10).
"hope that makes it clearer".