Except there is much more to a sport than, for example, shooting a basketball. There's offense, there's defense. There's fundamental skills, there's game strate

Except there is much more to a sport than, for example, shooting a basketball. There's offense, there's defense. There's fundamental skills, there's game strategy, there's different sorts of matchups. It goes on and on to subtler and more intricate detail. It's not simply whether one can skateboard or not, program or not, and it would seem that is what the author of the article was getting at. In your visual arts examples, there is a much simpler explanation. The reason there are more pages devoted toward layout principles is because the medium of expression (i.e. the web) fundamentally uses layout principles. Drawing doesn't express using the web. It's a selection effect, just as it's more likely that you will find soccer players in Brazil, and hockey players in Canada, rather than the other way around.