Actually, it is a technique regularly used by UConn rebounders when they cannot reach the ball to grasp it. It only takes fingertips to redirect it. Dolson, Faris, KML, along with Maya in the past frequently did or do tip the ball out to teammates denying the opponent the rebound and keeping it alive. It is a technique practiced by teams in tip drills. Your awareness of basketball drills and skills seems limited if you think that rebounding is only about grabbing the ball. As was, also, noted Dolson often screens opponents off the boards allowing Faris and other players to sweep up the boards. These are standard team rebounding techniques that depend on united function of players. If you would like recommendations of drills teaching this I can recommend Pat Anderson's material.