Old news. In actuality, he had 18 number 1's on the pop charts if you go by the standards of the day, including Hound Dog. If you go by today's standards, he had 14. In my opinion, you can't change the rules in the middle of the game and penalize documented results from the past. However, Billboard seems to do this on a daily basis. One of the many reasons it is no longer relevant.
Keep in mind, if there were digital downloads in the 50's, we'd be talking about the 45 songs that hit number 1 for Elvis, not 18....or 14.
Also keep in mind, Billboard was not the only major publication that utilized charts back in the 50's, 60's and 70's.