Your credit score is designed to tell lenders how much debt you have and how good you are at paying off your debts.  Buying things with cash is very responsible in its own way, but it does not tell the lender what to expect from you if they loan you money.  If you do apply for loans, the fact that you own your home and your car free and clear will be points in your favor, it just is not reflected in the credit score, which is designed for a different purpose.