There are people who are interested in population genetics as a discipline (usually academics) whom it behooves to try to be as objective as possible for the sake of their careers, there are people who are interested in exploring their ancestral lineages and the history of their people who by nature or training try to approach the material with honesty and integrity, and then there is the unfortunate underbelly of the population genetics world, which is made up of either ultra-nationalist or racist (sometimes the two go together) people who could care less about the objective reality and are only interested in manipulating the data or the interpretation of the data so as to make their own "group" superior by their distorted standards.
You can add to that the fact that some men, particularly young men, treat every discussion as a duel for dominance over other men, and you can then get edifying conversations like the one on this thread. It's irritating and boring to have to read, like being a lunch room monitor in a boys' middle school, but there you have it.
Very helpful summary of where the debate stands as to E-V13. I think ancient dna will give us more clarity, although even then there may be some ambiguity. As to the other clades of "E", there is even more ambiguity. There is indeed more diversity in Italy than in the Balkans. Is diversity an indication of "origin"? Perhaps, in some cases. Is diversity a sign of gene flow into an area? Sometimes, particularly if that place was a world power. There's also the fact that there has been gene flow back and forth along the Mediterranean, from Gibraltar to the eastern Med, for millennia, just as there has been gene flow back and forth across the north European plain and the steppe for millennia. I think it should now be clear that one can't explain the populating of Europe with neat, little, one directional arrows.
So, I don't know. No one knows; we're just speculating.