I recall Buck talking about this often. To paraphrase, he was in favor of pitchers being able to use substances to command the ball. He felt the balls were the issue, and wanted MLB to switch to the Japanese baseball which he described as tackier and able to be gripped without needing any foreign substances.
I agree about the distinction of things pitchers do to improve their grip (rosin, sunscreen, pine tar) being ok and should be at least tacitly approved or decriminalized. But things pitchers do to doctor the baseball (thumb tacks, sand paper, emory board, etc) to make it spin and move more after release is cheating. There is probably a tough distinction between the two in many cases depending on what is being used and how it is being used. I haven't read much on what pitchers might be being using now to increase spin rates, but if some sort of glues or tacky substances are staying on the ball to make it spin more, or being used to create leverage to directly lead to higher movement, that should be stopped.