The big thing I believe that is missing from many CrossFit athletes training programs is the development of upper body strength via either bench press/shoulder press (and their variations) and bodybuilding.
The main reason why more should be used is to increase performance in overhead barbell lifts or gymnastics. If your weighted improves it means that will carry over to your kipping pull ups making them feel easier.
Also a stronger muscle is more resilient to injury and can withstand degrees of stress. Based on the nature of CrossFit and the amount of wear and tear there is on the shoulder especially during kipping, it makes sense to develop a robust shoulder girdle.
Lastly, do people really think elite CrossFit athletes are as jacked as they are from only doing CrossFit workout, not a chance!