It is true that, in general, rank is not necessarily an absolute indicator of skill level. Moreover, for example, a sport jiu jitsu gi competitor may not necessarily be able to effectively apply his game to the no-gi or mma scenario.
To me, however, when said by people that are not practioners of jiu jitsu themselves, this quote comes off a little disrespectful. To me it’s like talking about how good of a soldier someone who was awarded a purple heart is. It doesn’t matter how “good” of a soldier someone is, the purple heart in itself deserves respect and honor. A man that was awarded a purple heart is a hero, no matter how accurate he might be at a shooting range or mentally sharp in a combat situation.
A jiu jitsu black belt is a mark of years of dedication to a sport, art form, and way of life.
Perhaps I’m being overly sensitive, but when an MMA commentator says “there are black belts, and then there are BLACK BELTS”, I cringe. I think there a better ways of saying the same thing, without disrespecting this tremendous accomplishment.