I see it is still being perpetuated, and it simply is not true
First off, Knoche quickly dispatched the old wives' tale that the surface of the tire needs to be scuffed or roughed up to offer grip. "Maybe it's coming from the old days when people were spraying mold release on the tread when the molds were maybe not that precise," Knoche speculates, "and the machinery was not that precise. But nowadays molds are typically coated with Teflon or other surface treatments. The release you put in there (in the sidewall area only, not the tread) is for like baking a cake, you know, so that it fills all the little corners and today that is done more mechanically than by spraying. The sidewall is important because you have all the engraving in the sidewall [with tire size, inflation pressure and certifications] and that you want to look nicely on your tire, so that's why we still spray the mold release there."
The next myth we see perpetuated nearly every time we watch the warm-up lap to a race. Riders begin weaving back and forth in apparent attempt to scuff the tread surface (which we've already discounted) and generate heat. The reality is that, according to every tire engineer that I've asked, there are far more effective ways of generating heat in a tire that are also much safer. Rather than weaving back and forth-which does little in the way of generating heat but does put you at risk asking for cornering grip from tires before they're up to temperature-you're far better off using strong acceleration and braking forces, and using them while upright, not leaned over! Acceleration and braking forces impart far more flex to the tire carcass, which is what generates the heat that then transfers to the tread compound as well (you often see Formula 1 cars weaving violently back and forth because automobile
tires operate on a horizontal plane, so they have and use significant sidewall flex to generate heat).