I don't think that post requires they be equal, or even equivalent. It more questions whether they are being made analogous, which they could be. You could look at 1st degree as graduating HS in some systems or as an undegrad degree in others. Each progressive "degree" rank would be analogous to the progressive degree system in US higher education.This question assumes that earning a black belt is equal to earning a college degree. Four years of full time study, 120 credits, the first 60 of which are the core curriculum classes consisting of hard science electives, literature, humanities, mathematics, etc. Where the entire curriculum of most Japanese and Korean martial arts up to 1st Dan are on just a few pages (maybe 5 to 10), you have a 500 page textbook for each 3-credit class in college. They're not the same.
Yeah, but you have no way of knowing how many hours these students are studying on their own time, or even if they are at all. Every student is different, and some are fully capable of excelling with little or no self-study time.