Yes, many stupid people simply use them for new experiences. But someone already smart can use those new perspectives to gain a better understanding of reality.
I personally know a world renowned mathematician who solved a problem that was thought impossible. He used LSD to approach it from a new perspective and holds one of the highest prizes in mathematics.
Francis Crick also admitted to frequently using psychedelics to expand his thoughts. His first vision of the DNA double helix was under the influence of LSD(he literally ran out of the laboratory shouting about his discovery). It was 100% legal then.
Countless other scientists and inventors have had a fondness for psychedelics. Adding even one new perspective to your work can make all the difference.
Syd Barrett made Pink Floyd a success by wigging out on it, thereby prompting many PF albums about Syd Barrett wigging out on it.