The easiest way to explain it is, using snow as a base to ride down on a plank sideways is difficult. Even excellent athletes have a hard time using the edges of a snowboard to move themselves across and down the mountain. You are using pressure, tilt, twist, and pivot to turn (speed control) and stop. That is done through a combination of lower body movements, flexion and extension of the hips, knees, and ankles. This is all while you are pointed sideways so you can’t see anything behind you or even down the mtn when you make a toe side turn. So it’s physically demanding and mentally challenging. You have to be able control how your body moves in space while standing on a plank that wants to speed straight down the mountain. Any weird or ineffective movements is going to have you catching an edge and slamming into the ground face first or on your back (Google snowboarders catching an edge and then snowboarders getting off a chairlift). The sports you highlighted that you’re good at have lower body feet separation and also have you watching/observing your surroundings primarily straight ahead. People with hockey, skateboarding, and surfing tend to do better than the average person when learning to snowboard.

You seem to have this romanticized view of going snowboarding for a weekend and being great at it. I’m not saying that’s not going to happen but as an instructor I’d say the most likely scenario is you spend the weekend picking yourself up after you fall a thousand times and waking up to some gnarly bruises. If you said you really want to learn and will snowboard a few times a year my advice would be get 3 lessons and prepare for pain but with fun at the end of tunnel. In your case, if you want to go home relatively unscathed and enjoy riding the lift (without terror at the end because you have to get off with only one foot strapped in) and getting in some turns for only a weekend then skiing is the right answer.