I don't disagree with you, but frankly would be a bit frustrating to limit one's studies of human behavior to just history without trying to understand the dynamics of current societies, trying to understand how they respond to change and so on. Both fields have a completely different set of instruments and very limited overlap.
The best social science studies involve often accidental experiments, where good experimental conditions occur not because of design but because of happenstance. The analysis of these situations could be construed as a historical case study, or it could be construed as an experiment. I agree that seeing analogues in past societies is not the best approach, but studying history can sometimes reveal experiment-like conditions.
Another similar issue is with data from situations that would be clearly unethical to intentionally create. Behaviour of plane crash survivors standard on mountainsides, castaways, feral children, etc
