Sure, if the object was declared const in the first place, then it (mostly) can't be mutated. But the real power of const comes from const references, which in

Sure, if the object was declared const in the first place, then it (mostly) can't be mutated. But the real power of const comes from const references, which in Rust guarantee that the referenced object will not be mutated while the reference is alive, even though it might have been mutated before.