Bowlers and bowling officials can argue about what the minimum hardness for a bowling ball should be, and whether there should be different rules for different kinds of balls.
What is inarguable is that a point of hardness does matter in ball motion, according to Ronald Hickland, who worked at and designed balls for EBI and now operates Creating the Difference.
Back in March, CTD posted an eye-opening blog and video, The Effects of Bowling Ball Hardness: What is Special About the Purple...