TEPaul,
Sometimes a position, taken by an individual, masks the true reasons behind their stance.
Just putt a ball into the grain around the green, then putt a ball with the grain around the green, and you notice quite a difference.
When carts are restricted to the rough, it isn't long before the grass is going toward the green, making the extracation of the ball from the rough much much easier.
I have to believe, with new grasses, old grasses, and middle aged grasses, that if the gangmowers repeat their pattern of down one side and into the other. that it will make a difference.
And.... if the pro's felt that way, the guys who do this for a living, I would have to go with them.