There were 116 male competitors in the October Iron Fest we put on last year. I just did a quick scan of the PDF results and I counted 8 people that squatted 500 pounds or greater. I don't have the Excel data in front of me and I was not being very careful, so I reserve the right to have miscounted one or two people. The competitors there were not, for the most part, highly competitive powerlifters.
Let's take a look at USAPL's Raw National Results from 2014. Three-hundred and fifty-one men competed and 123, or 35%, of them squatted 500 pounds or greater. A dude weighing just under 140 pounds was among those who did, as did one woman. Seventy-five of the men opened with 500 pounds or more on the squat. Raw Nationals attracts good lifters, including some who are internationally competitive, although the majority of the lifters there are not world class athletes. It also nominally reduces the number of competitors that are on drugs.
A 500-pound squat for a reasonably large young man is not a mythical accomplishment. It is the product of a lot of hard work and it is a significant display of strength, but a lot of people have the ability to do it. If a 500 pound squat is remarkable, many remarks must have been made during Raw Nationals last year. A one armed chin is a function of good arm strength at a light bodyweight. Climbers, as Mr. Miller pointed out, are a group of athletes that manage this. The combination of a small frame and strength is probably more rare than a high level of force production regardless of bodyweight.