This documentation page is extremely misleading for many users:
https://docs.unity3d.com/Documentation/Manual/BlenderAndRigify.html

This gives the impression as if Rigify can be compatible with Mecanim. The issue is that once the described steps from the document are performed, the rig in not anymore usable in Blender. In fact, with that destructive workflow one can also use the Rigify's meta rig which would save a lot of time at the end.