Sure they can. It doesn't always work, but that doesn't mean it never works. You might as well say that seatbelts don't work because you can cite a few cases

Sure they can. It doesn't always work, but that doesn't mean it never works. You might as well say that seatbelts don't work because you can cite a few cases where people died anyway. And if popular support were really overwhelmingly in one direction, a constitutional amendment can change what the constitution says. Constitutional amendments can make the unconstitutional become constitutional, and vice versa. Constitutional amendments aren't easy to pass, but that's by design. The constitution should only be amended when popular support is overwhelmingly in favor of it, and when that occurs, it's possible.