I've been thinking back to the history of our sport, and if I'm not mistaken surfing is the og sport that evolved into skateboarders ripping up backyard pools. Skateboarding and skateparks (and snowboarders) seems like the obvious reason we have rails and features on the mountain.
But were urban street skaters in the 80-90s really the first to hop and a rail? Maybe we gotta give more credit to froot booting inline skaters as being forerunners to modern park skiing. Or maybe some old timey skier in your grandfather's era used to impress the ladies skiing a picnic table or down a wooden handrail. Or did Tom Wallisch just invent sliding rails when he started the universe with the big afterbang?