Do you follow skateboarding? Do you know how many specific competitions are regulated by testing? There are a LOT of competitions, my friend, and not all test.
You are correct about the testing results but that other poster is correct. Most actively competing skateboarders smoke weed. Maybe not as often as you would think but it is pretty out in the open within the community to this day.
Yes, certain well-established skaters from back in the day stopped partying altogether but most of the younger active generation smokes, drinks, and does god knows what else. Just not quite as often as people assume.