I agree with all you said. I found an interesting thread on this very topic from 2011-old! But CC was much more active then and I think it gave a good cross section of applicants in this category. Most seemed to get admitted which was hopeful. But, I’m not sure how representative this is for current times.
I think they are creating the threshold as they go so those applicants just a bit above last year’s threshold end up in this category until they complete their review. But, there is certainly randomness and inconsistency!