His point was more along the lines of it being poorly designed.
Evolution isn't going to nicely separate functionality into clean, single-purpose biochemical pathways.
It's going to overload something that it already has to support a new feature, leading to a rat's nest of intertwined effects.
The hard part in drug development isn't affecting your target: that's pretty easy to guarantee with modern tools. It's finding out that that target also governs 10 other, completely unrelated bodily functions.
