Productively inefficient refers to a situation where a firm or an economy is not producing goods and services at the lowest possible cost, leading to wasted resources. In the context of monopolistic competition, firms often do not operate at their minimum average total cost due to the presence of excess capacity, which can result from having a downward-sloping demand curve. This inefficiency is inherent in monopolistic competition because firms have some degree of market power, allowing them to set prices above marginal costs and producing less than the optimal quantity.