Now that's some bad advice!
Grip size should be personal, and your choice.
Baseliners normally prefer small, with heavier rackets.
Net players can prefer the size they want.
Mi*******s can solve the problem by adding bigger grips or heavier racketweights, or watch the ball more closely.
Small gripsizes, -3/8. are fine for some, poison to other's.
I use 4 5/8th with an overgrip, and nobody ever accused me of hitting to softly, any tennis stroke.