Yes it really is a case of there not being able to see the forest for all those trees! The sheer volume of people (as a percentage of the global whole) is so large they cannot be ignored. And when these "Celts" appear at the same time and same place the large volume of Northern Kingdom Israelites disappear, it makes ignoring the evidence impossible.
These lefties deny that Reaganomics increased wealth for America, so they'll continue to deny that the Israelites played a signigicant role in history.