Worst advice ever. A credit score is not just for getting a mortgage or a car loan. When I lived in New York, I had to have an acceptable credit score to get an apartment in most places.
Not to mention, when I signed up for a Verizon account under an LLC that I have with my dad, we were forced to put down an $800 per phone deposit because the company had no credit history. Same with utilities.
When I was starting a company, the bank wanted to check my credit score to decide whether I was going to get a checking account or not. This has happened twice, once with my previous company and a merchant account for credit cards.
I haven't ever personally, but I've also talked to people who check credit scores as part of employment evaluation.
Also, having a higher credit score gets you a better interest rate if you do need a loan, which can be worth a whole lot of money.
You have every right to make the choice to live without credit, but I would have a hard time arguing that it's the smart play.