Many of the most famous personal finance gurus are basically teaching "personal finance for dummies", and so they take a very basic approach. They focus on gett

Many of the most famous personal finance gurus are basically teaching "personal finance for dummies", and so they take a very basic approach. They focus on getting people out of financial trouble, and in that context 'debt=bad' is a pretty handy rule of thumb. If they gave the general advice to chase that sweet 3% cash back, they could easily do more harm than good to their audience at large, since it might lead a large number of people (remember their target audience!) to take on debt that they end up carrying for some time. By sticking to the over-simplified "debt=bad" messaging, they give up some easy (small) gains to avoid some potential (and relatively big) costs.