Why doesn't Visual Studio allow me to step into Type.GetType()?

I've got the following simple code:

class Program
{
    static void Main(string[] args)
    {
        var t = Type.GetType("System.Reflection.Assembly");

        Console.WriteLine(t.FullName);
    }
}

I'm attempting to debug into the Type.GetType() method, but the debugger skips over the method even when using "Step Into". I've got debugging enabled for the .NET Framework classes, and debugging into other framework methods works fine. Why doesn't the debugger allow me to step into this particular method?