Development of competence in sports obviously requires actual playing but I think we have not recognized the value of watching. I think that it is no accident that ALL accomplished athletes had been (and mostly still are) sports fans.
I can’t discuss soccer. I have never played or watched it. But I can talk about other sports.
Baseball: When I was ten (circa 1950), I had acquired all the mannerisms of the entire Chicago Cubs players, both functional and nonfunctional. Nobody had to teach me the basics of throwing, catching and hitting. It came “naturally,” that is, it was acquired, not through trial and error in throwing and catching and hitting, but largely from watching.
There was an element of instruction, and what I learned consciously often did help, but it was extra, fine-tuning: e.g. keep your eye on the ball. And of course we consciously learned elements of strategy, eg the catcher should back up the first baseman, and less observable elements, such as efficient sliding.
But most of it felt natural and even felt like they were innate. If we were right handed, we didn’t step forward with our right leg when throwing.
When we watched baseball, we didn’t watch for form, eg notice the second baseman throwing the runner out side-arm, not overhead. We watched the game, rooting for our team.
I also noticed the improvement in form when martial arts movies became popular. I had tried judo and a little karate in the late 1960’s and it always felt odd. But Bruce Lee, Jackie Chan and Chuck Norris made a difference. We all improved. When a local theater had a martial arts festival, showing the same three movies all weekend, nearly everyone from our Tae Kwon Do studio was there nearly the entire time. NOBODY was interested in details of style, it was pleasure watching.