I disagree. Most kids need to be forced a bit to learn something hard. Sure the kid who likes sports should play. However only exceptional kids will ever be good enough to make a good future playing sports. Most kids will grow up to realize that much as they love the game they will never make a living at it. Thus we need to ensure those kids don't spend all their time getting better, but instead spend time getting useful life skills that they will need as an adult. Much as "post scarcity" people like to think otherwise, we are still not in a world where many people can "slack off".

Kids learning how to develop themselves is a good thing ONLY if they choose the "right thing" to develop. You can get really good at video games, but as you already said probably not a good only investment (a fine hobby, but keep it a limited time hobby). There are some sports that because of injuries should really be banned (but I won't list them because as soon as I do there will be a lot screaming from people who live that sport). What we need is kids who develop themselves into something that makes them good productive adults - for some jobs we need adults to do this is boring and so kids won't do it unless forced.