Less than 5% of the population can do a pull-up. I can after having climbed for a bit and worked towards doing it, but you might be surprised to learn how few this would actually benefit.
This is where calisthenics comes into play. You can quite easily increase and decrease the leverage on the muscle to workup to the 'main exercise' and even past it. IE, for pull ups, you can hang under a table and do a 'horizontal' pull, you can 'cheat' up the movement (jumping), you can use resistance bands, etc. This is the same for almost every muscle group.