Because she isn’t? Sure she’s better than any of the Republicans, but that’s a stupid low bar and doesn’t really tell you much. Her record in California is abysmal, she had zero support in her campaign, and she’s done fuck all since she became VP. She’s essentially a glorified security barrier to stand between the nuclear codes and whatever asshat the Republicans end up shoving in as Speaker in the event that Biden goes the way of all flesh during his term.