The possibility of getting lucky is a poor thing on which to base a claim that modelling internal mechanisms is unnecessary.

Gives failure rates of >90 any getting a drug through clinical trials is always "getting lucky".

The issue depends on how much successful drugs are successful do to understanding of the pathways and how many are successful because of luck and good empirical measurement of effects of drugs.

I personally think that medicine would be improved if we would reroute capital currently trying to understand pathways to researching better ways of empirical measurement.