False. Experts don’t understand many drugs and still prescribe it. And it’s a good thing.
The software analog of settling merely for "it seems to work" would be if someone were to hand you a bare binary whose behavior must be inferred entirely through black box testing, without source code, architecture diagrams, or any other documentation. Sure, users can try running it in a pinch, which is the case for various medications, but it's surely possible to do better in the long run.