I have to disagree with what you are saying.  I have experienced this first hand.  Several years ago I paid off all of my dept and decided I would close an account that I had not been using.  This account happened to be an account that I had opened back in the early 80's.  Immediately after doing this I was advised (within a month) by my car insurance company that my new renewal rate had increased by a couple hundred dollars because of a significant drop in my credit score.  I reached out to experian at the time and they advised me that this was because I closed the account that showed my longest credit history.   My advise is DON'T DO IT!  It has taken me a long time to try to repair this.