It's to keep the page weight balanced. Prose is considered to have neutral buoyancy, but code is naturally heavier and will tend to drag the page down if that i

It's to keep the page weight balanced. Prose is considered to have neutral buoyancy, but code is naturally heavier and will tend to drag the page down if that isn't compensated by a lighter font. FWIW poetry can be so light, that it can require a very heavy font weight to keep it tethered to the page.