I think his idea of living without debt is doable but not for most. If most people waited to buy things in cash (house, car, school, etc.) they may literally be waiting so long that they can’t enjoy it or may never obtain it. Income is a huge factor and sometimes you need that debt in order to make more money (business loan, school loan, house – wealth building).
I think either debt pay down method is fine. I like snowball because of instant gratification and the avalanche method may disappoint my need to see instant improvement.
To me it’s all individual and I’m not a fan of grouping people into the same methods and plans. Credit and debt is too specific to the person for that.