That's true, but I was in a bad way after wrapping my hand around the fretboard and using my thumb for root notes in barchords (ala hendrix) for 3 years. Felt normal but think of how cramped my hand was. I was out for 6 months and had to change the way I played which took a while. I guess if John Petrucci has played that way since he was however young then I'm safe.