Credit is not a good or evil thing. It accelerates things; so if used badly, it accelerates the crash and burn; but when used intelligently, it accelerates your growth. Don't know how anyone could save the $400k for an average home or even the $200k for a very below average market price home.
I have encouraged my 18 y/o son to get a credit card, and charge only gas on it, and pay it every month. At some point, he's going to want to buy a car, and the odds of anyone just having $18k or so, or more, just sitting around is very low. Heck, if your credit is too low, you may need a co-signer or massive deposit just to get a electric service set up in your name, or rent a place to stay.
Careful following Dave Ramsey, he has some good points for sure, but he's a fanatic, who makes money off selling his koolaid.