There is no exception for ANY data structure that includes references to other data structures or primitives. Not only can you add or remove elements from an array, you can change them in place.

A const variable that refers to an array is a const variable. The array is still mutable. That's not an exception, its also how a plain-old JavaScript object works: You can add and remove properties at will. You can change its prototype to point to something else and completely change its inheritance chain. And it could be a const variable to an unfrozen POJO all along.

That is not an exception to how things work, its how every reference works.