The question of how to demonstrate the clinical benefit of a medical device may initially sound like a purely methodological issue. In fact, it determines which products remain available in Europe, how long approval procedures take, and how much effort manufacturers must invest in clinical evaluation. In the context of the ongoing MDR revision, this discussion is becoming significantly more intense, as not every product can be meaningfully evaluated using the same standards. It is particularly challenging to evaluate products whose contribution to treatment success cannot be directly reflected in patient-centered clinical endpoints. These include surgical instruments, endoscopes, catheters, operating tables, and numerous other products that enable or support diagnostic or therapeutic procedures in the first place. For these products, an understanding of the evidence is needed that does justice to their actual mechanism of action.