I will agree with you if Last Gleaming reveals that all that exposition was meant to be anything other than mumbo-jumbo claptrap. But it played well as mumbo-jumbo claptrap, so I'm holding out space for it to be meant as that. Giles said nobody knows, and it read like, in fact, nobody knows. We're told in the text that Willow is guessing, Angel is guessing and Giles is guessing. So I think it's possible that they really are just guessing.