I agree it is a waste of talent, but what quants are supposed to be doing is predicting the market (their ultimate goal is do construct a profitable trading str

I agree it is a waste of talent, but what quants are supposed to be doing is predicting the market (their ultimate goal is do construct a profitable trading strategy, but this is roughly equivalent to predicting the market). So it is quite straightforward to test them, in principle. In practice, data snooping makes it hard to really test quant trading strategies, and as a purely practical matter trades have small effects on the market which makes it hard to test a trading strategy without actually doing it.