I actually explained earlier why you want to use chalk instead of some sticky compound on your cue. The main reason is consistency. Rubber will behave differently as it ages, it’s got too much flexibility which will cause the shape of the contact point to change, and its stickiness will change depending on impurities - finger oil, humidity, dirt from hitting various balls multiple times, etc.
Chalk is always fresh and consistent in texture. Applying a thin layer of chalk before each shot guarantees perfect consistency in the amount of friction the cue tip imparts to the ball.
There seems to be a misconception here that ‘springy’ is what you want in a cue tip - hence the belief that rubber would be a good material. But most serious players play with tips that are extremely hard. Springiness is not an advantage, because it leads to inconsistency. A hard cue tip with chalk on it provides a precise amount of force with a precise amount of friction to the exact area of the cue ball you want to hit. It’s simply a much better tip material than any rubber to date.