ITestMethod in Microsoft.VisualStudio.TestPlatform.TestFramework: who cares?

I'm playing a little with the Visual Studio testing object model (2017 Community Edition, but I don't think this is the problem...).

I noticed that in the Microsoft.VisualStudio.TestTools.UnitTesting namespace of the Microsoft.VisualStudio.TestPlatform.TestFramework assembly exists the interface "ITestMethod" that can be passed to many attributes methods to be executed... At the beginning I thought that this is the way followed by Visual Studio to run test methods, but it seems that no one implements it...

So strange... any idea about it?

Regards, Attilio