Don't think for half a second that Ken doesn't understand VMG. He grew up racing on Narragansett Bay (shifty and puffy like a lake, with extremely variable currents), and has done a few stints in the VOR.
Unless you're on a piece of water with no current or wind shifts; VMG, like boatspeed, is something to consider, but may not always be the priority. There are times when you may prioritize one of these over the other, or sacrifice both for another goal, like placement vs your competition, or preparation for an expected shift in wind or current, etc.
Wind forecast for tomorrow says low teens, should be fun!
Mike
That was tongue in cheek - clearly the guy knows VMG with his experience.