Taytum is great in the paint on offense even though he regularly was defended by 4s. And he usually guarded 4s himself. He was great on the boards.
You can call him a SF if you like; that's not how he was used. He was used as a 4 all season. And as much as I hate all things Duke, I can recognize that he is one of the few in the country who isn't an either or as I posited in the OP. He can hit a 3 and play big inside on offense and board well. Ugh, I feel dirty even saying that about a Dookie.