I think you are making it all up. Nicklaus couldn't swing like Hogan because Hogan had the almost perfect swing and all Nicklaus could do is win with his inferior motion...lol. Hogan didn't have a flat swing it just wasn't as upright.
Hogan had as flat a swing as anyone where it mattered...he famously laid off the club in the transition.This requires a clockwise rotation of the left forearm to start the downswing.I have no idea how these players can consistently tumble the club back to square in such a short period of time.The rotational skill required is unbelievable.
You readers out there in amateur land forget it.