Energy! Businesses alone can't negotiate with foreign powers and dictatorships who control most of the oil reserves.
Tillerson effectively cuts out the middle man. He'll be the point man diplomatically with other nations so that businesses can focus on businesses and not worry about their personnel getting kidnapped in Nigeria or something.
Speaking of Levin, he's persona non grata to me. I donated all of his books I had bought to Goodwill. I no longer listen to his show nor click on the daily Levin thread here.
Not that he can tell Exxon what to do, but he knows in-depth the national and global reserves, avenues of distribution, and production capacity of the good-ole' USofA versus all else.