Does not the prohibition of Riba al-Fadl (usury of surplus/increase) inflict greater injustice upon the buyer in some cases, and fail to achieve the desired mutual benefit?

Usury (riba) is forbidden by Islamic law unanimously and is considered one of the major sins. It is of three types: Riba al-Fadl (usury of surplus), Riba al-Yad (usury of hand/spot), and Riba al-Nasi'ah (usury of delay/deferment). Wisdoms have been expressed for the prohibition of usury, among them: that it is a sale for an increase without a counter-value, and that it leads to the stagnation of trade and work, severs kindness and benevolence among people, harms the poor, and all forms of usury are reducible to these three types. A Muslim must submit to the commands of Allah, whether or not he comprehends the wisdom behind them.