By pulling the dent out, for decades the standard approach to eliminate scores was. You would need to drill holes to the dented area and make use of a tool to pull back the metal fit. Then make use of a body filler to smooth over them and you would have to grind down the holes. After that you'll repaint the damaged area and that is only one of the biggest drawbacks for this procedure. Without taking it back to the manufacturer, it is extremely difficult to duplicate it. That means you'll be left with a part of car that was obviously repainted with poor stuff.
Paintless Dent Repair was devised specifically for this reason. The Mercedes-Benz Company in Germany was having plenty of trouble shipping their cars to the assorted dealers. When they arrived they would have dings and dents but the car lot would not have the resources to give them a manufacturing company quality paint job after they were repaired. So they really developed a procedure for Paintless Dent Removal which uses poles to push the score out from the entire interior while lightly tapping the outside with a hammer. It really is very important that the technician be very proficient because when they strike the metal too hard it'll divide, using Paintless Dent Repair techniques. Occasionally rather than shoving with sticks which can get rid of the requirement for using a hammer glue is used on the outside of the car to pull the score. The only times that Paintless Dent Removal is not possible is when the original impact damaged the paint or if the metal has been stretched too much out of shape.