It works if you only ever need to reference the outer value, but it doesn't allow you to e.g. get a working mutable reference to a field inside a struct - even

It works if you only ever need to reference the outer value, but it doesn't allow you to e.g. get a working mutable reference to a field inside a struct - even if you declare the field as another Cell<T>, when you read the value from the outer cell, you get a copy, not a reference to original. And the same thing goes for arrays, which is especially inconvenient. So no, not quite equivalent.