If, as you say, you pay cash for everything, then you would have a low credit rating. Why do you possess an ‘unlimited’ Mastercard Johnny Cash?
I consider paying a credit card bill in full the day it’s received the same as cash.
I first got one when I found out 50 years agio that you can’t rent a car without one.
I needed one for 3 days for my wife when I was repairing her car and couldn’t rent one even ofering to put up the full value of the car in cash.
I also use the card for purchases at FBOS since 5% goes to AOPA’s air safety foundation.