is it because of the Israel lobby, or because Israel serves some sort of strategic purpose?

Mearsheimer seems to think that it's mostly because of the lobby. I think I agree with him; I really can't think of any unique strategic purpose that Israel serves for the US. if Israel disappears tomorrow, the US still has colossal military bases in the Gulf states, it still has friendly governments in Jordan and Egypt, it occupies Syria and Iraq, it has ISIS to stage crazy terrorist attacks, etc. what exactly does Israel do that's worth all the negatives for the US?

I watched Finkelstein's recent interview on Al Jazeera and he mentioned he disagreed with Mearsheimer. just curious what everyone here thinks.