If the system were typologically common, as proposed by the glottalic theory, it might be expected to be stable and so be preserved in at least some of the daughter languages, which is not the case: no daughter language preserves ejective sounds in places that the theory postulates them.
Agora, se o sistema fose tipoloxicamente corrente, como propón a teoría glotal, entón habería que esperar que fose estábel e, por tanto, que se conservase en polo menos algunha das linguas fillas, cousa que non é o caso: ningunha lingua filla conserva sons exectivos onde a teoría glotal os postula.