There are admittedly a few ways to measure exclusivity and define openness.
If you account for applicant quality in how you measure exclusivity:
NSF fellowships, top medical schools, top JD programs, top science PhD programs, many jobs, some country clubs,
The Rhodes and Marshall scholarships come to mind as "most exclusive." They're arguably not "open application" due to age requirements. I suspect YC has an age requirement too, but it is less restrictive (and less explicit.)
If you don't control for applicant quality, then even entry-level jobs are more exclusive than YC. I've been in charge of hiring for a jobs where we made job offers to less than 0.5% of applicants. Which is just to say that acceptance rate alone isn't the right metric.
I think I'm touching on a small sliver of the "most exclusive things" list. The fact that most of the world hasn't heard of YC would also suggest that there are also exclusive programs in other fields that we aren't familiar with.
I agree that YC's requirements are more flexible than most jobs.
If you don't have the skills to do statistical modeling, we wouldn't hire you. We gave guidance in the job posting about who was a good candidate. But we didn't prevent anyone from applying.
YC is the same in all those dimensions. If you don't have the skills necessary to build a successful startup, they won't accept you. YC gives guidance on their web page about who was a good candidate. But they don't prevent anyone from applying.
I'm not sure how you define "open" so that one of those qualifies and the other does not. If "open" just means that they have more flexible requirements, that is a difference of degree, not kind.
YC is an unusual combination of selective and eclectic. But claims about "the most selective open application in the world" suggests a lack of perspective.
If you account for applicant quality in how you measure exclusivity: NSF fellowships, top medical schools, top JD programs, top science PhD programs, many jobs, some country clubs,
The Rhodes and Marshall scholarships come to mind as "most exclusive." They're arguably not "open application" due to age requirements. I suspect YC has an age requirement too, but it is less restrictive (and less explicit.)
If you don't control for applicant quality, then even entry-level jobs are more exclusive than YC. I've been in charge of hiring for a jobs where we made job offers to less than 0.5% of applicants. Which is just to say that acceptance rate alone isn't the right metric.
I think I'm touching on a small sliver of the "most exclusive things" list. The fact that most of the world hasn't heard of YC would also suggest that there are also exclusive programs in other fields that we aren't familiar with.