Tipping a shaft actually stiffens the TIP. Not the entire shaft. This stiffness will help keep the ball down and avoid ballooning. When the shaft unloads the tip will "flick" the ball in the air. If its too soft with a high swing speed itll flick more, creating more spin. And the ball will go too high.

Pros with high swing speeds tip their shafts. Its just one more factor they focus on in trying to deal with such a high swing speed. Naturally a high swing speed will create more spin and the ball will go higher. So they find a low spinning head, tip the shaft and couple other things to eliminate spin.

Tipping a shaft doesnt normally affect sidespin. Just overall spin. Sidespin is usually the golfers issue not the shaft. Its a face to path relationship.

Any pro can hit a decent shot with any shaft. Its just that it will go way higher than they want. Ammies who have very slow speeds actually need help and a softer tip will get it up in the air.

Work on your swing path and face control. Stiffness of shaft isnt as important as people think especially with moderate to low swing speeds. Look up on youtube and youll find many people debunking this. Usually at the end of the day an overall stiffness of a shaft is about preference and feel.