How do you propose then to isolate what may be the effect of the drug then vs the participant subconsciously trying to act out what they think the drug is supposed to make them do?
Compare to a less politically contentious human performance question, like, should a point guard do strength training to increase upper body strength? This is a topic where expert thinking has evolved during my lifetime. In the 80's many people thought that strength training would mess up shooting ability. Nowadays the consensus is that strength training is good, and that basically all NBA players should do it.
Nobody did studies where secretly one set of basketball players worked out and got stronger arms, and the other half did "placebo workouts" that didn't make them any stronger. It's just obviously impossible to do that sort of study. I think it's equally impossible to do a good study on Adderall with placebos. But we still learn over time, by having experts try out different things, analyze the results subjectively, and discuss and share the outcomes.
What I would like to see is making study drugs like Adderall and Modafinil legal, and for people to openly share their experiences, positive and negative. I think over time our society would learn from that and grow wiser, even if formal studies never quite worked.
I don't really see the point in this being a lab experiment, just test the results from actual people who use study drugs (not saying naturalistic experiments aren't biased in many ways too, but seems like a better option).