Svelte 5 introduce runes, and recommends now to write:

let foo = $state(42);

instead of the elegant

let foo = 42;

I can understand why it makes sense in React… but since svelte is a compiler, why can’t it automatically compile let foo = 42; into its rune equivalent? I guess that because sometimes one might NOT want to assign something via a rune… but it which case would a standard let be better than a “rune let”?