Consumer marketing would be a good example of something that has no long-term benefit because society changes too often. Marketing techniques that work in one decade won't work in the next. Because of this, marketing isn't cumulative. Our knowledge of the hard sciences is always improving, building on the work of the previous generations.

Yes, there are legitimate fields that don't have rigorous math behind them, but the social sciences try to use studies and numbers as the foundation of their theories. They want to be treated like biology, but their studies are not up to par.