The reason for the "500 sub" entry is simple. It's for content creators. Pretty much anyone serious about creating content will get 500 subs. Many folks have a youtube account but don't have any videos or only 3 videos in 5 years or so. If opened to them, then tons of folks would fill the spots that aren't even creators, while folks that create content and have 100,000 subs are on the outside looking in.