EMF is not a language because it should be spoken by at least two persons.
I have never seen two architect talking about the same ecore diagram and
the best practices how to display EMF model elements. Only code generation
from EMF and serialization are really used today.
The purpose of UML is to be a widely used language having a common sense
which is normalized by the OMG and the UML 2 specification.
EMF is not a language for me only is UML.