All credit cards and their rewards programs are designed to make you spend more.
Even if you do not carry a balance, you are spending more money because 'at least I can fly for free if I put this on my card.'
You end up finding more reasons to spend than 'just the necessities.'
I haven't had a credit card in 15 years, have zero debt, my business have zero debt, and I have an undeterminable credit score and I still was able to buy a second house, rent cars and hotel rooms with no problem.
Cash is king.