Many of these technological developments have occurred due to help high-skilled surfers improve their performance and safety precautions.
Factors that could have contributed to these developments could have been age, ability, weight, safety and conditions of waves. For example, the surfboard rail curve was designed for more skilled surfers to be able to maneuver faster and in more technical ways.
Another feature which evolved for two reasons was the leash. Firstly the leash provides a connection between the surfer and the board, so when getting wiped out you don’t loose your board in the surf. However the leash was also created so it wouldn’t injure anyone else out in the surf while floating around.
Biomechanics Of Surfing 