Earlier quoted context omitted.
Using credit cards does not preclude being able to afford the thing you are paying for. I regularly use my credit card for every day purchases despite having ample money in my checking account. The regular payments allow me to develop a good credit history without much worry.
Why can't you use a debit card for that? Isn't having enough money in your checking account to reasonably afford all stuff you need to live basically proof of a good credit history? Isn't the best credit history one where you never need credit in the first place?
Handling debt responsibly is a different skill from handling cash responsibly. When it comes time to buy a home, for example, which 99% of people will need credit to do, the banks want to see that you can handle debt responsibly, since that's what you're taking on.
Edit: Also, see my reply to GP comment that explains some of the other benefits of using a credit card.