Sports and art aren't superfluous: they teach gross and fine (respectively) motor skills. School isn't just about developing cognitive skills or brainwashing students into political orthodoxies: it's also about teaching students how to control their bodies in general and specific muscle groups, like the hands, in particular. Art is one way of training the hands; music is another (manipulating anything from a triangle to a violin), as is handwriting. Without that training. Students may well not get enough of that dexterity training at home, particularly in the age of tablets [0].

[0] https://www.bbc.com/news/technology-43230884