The const keyword has absolutely nothing to do with state mutability, that is a misconception. const in es6 is a keyword meant to explicitly prohibit identifier reassignment and it does indeed reduce bugs because it communicates developer intention regarding how a variable reference is expected to behave in a section of code. Further, use of const by default is a best practice because it leaves less room for error in cases where a reassignment must never occur and increases readability by convention of the let keyword signaling that a reference will behave in a volatile way in proximal logic.