If it’s uniformly heated, sure, the liquid is at max temperature. But even in a pot of just water, the convection isn’t that fast on its own. Bubbles move very fast, liquid does not. The top is cooler. Even the center of the bottom is cooler, as the vapor bubbles will primarily form in a ring the size of the burner. The non-bubbling vapor cools the surface water at the top and the pot walls cool from external airflow. While near-boiling water may effectively be as hot as it needs to be to cook pasta, there’s still gaps between boiling, rapidly boiling, and actually being at the boiling point uniformly