I don't think it is that simple Dave.
I think the main idea behind a DOF is to provide continuity to the club which is something we have been sadly lacking. We hire a manager, he spends lots of money on players, he gets sacked we hire a new manager we then have players to sell at a huge loss and we buy a new batch... rinse and repeat.
Carlo Ancelotti is in a different league to any manager the club has had since Kendall but the problem remains for the club. As I said I don't think CA will be a terribly long appointment but I believe he already has raised the bar for everything at the club.
I believe we need some players for a short term fix, but after that we need strategic long term planning between manager and DOF... I think this is how it should always be.
I think the attitude that it must be one or the other is a bit juvenile.