The components that make up a good song are so indefinable and abstract that it can't really be taught in the same way that painting or writing can. Obviously there's chord progressions that can be taught and they sound correct and stuff but a good chord progression doesn't automatically make a good song.
If a painter wants to paint a tree they paint a tree until they've painted a tree that they're happy with. But you can't really do the equivalent with music. You can't sketch a shit chorus and then paint it until it's good. There's something pretty peculiar about it. Much more innate ability required maybe.