Being the one who said that, it's probably fitting I answer.
It all depends on your definition of 'playing the man and not the board.' If by that you mean ignoring your opponent's moves and the demands of the position, gambling on an unsound attack, no good player does that, certainly no Grandmaster.
OTOH, every player has preferences for typical positions, and in preparing for a game against a known opponent, most top players will 'slant' their work a little, aiming to get positions they're comfortable playing that might be uncomfortable for their opponents.
The classic case of this has got to be Kramnik's revival of the Berlin Defense against Kasparov in their world title match. Kramnik knew Kasparov well, knew he didn't like queenless middlegames with lots of maneuvering. So he added the Berlin to his arsenal for that match, and he won.
Note the subtlety, though. Kramnik didn't play bad moves; the Berlin is a perfectly playable defense that only fell out of favor because it tended to draw far more than other lines.
In my coaching I've run into too many youths who use 'playing the player, not the board' as an excuse to play "hope chess," making bad moves to generate a silly attack that in reality has no hope of succeeding against anyone with more than two synapses firing.
My advice to them has always been: "Learn how to play the board, first. Then, when you're good enough to understand what positions you're comfortable in and how to tell when someone else isn't, and only then, start to consider playing the player. Because only then will you be able to do so with any real hope of success."