Lol I think we can all debate until the cows come home on this subject.
My 2 cents worth - JLC is a marker of prestige in lawyerdom because so few get it. A bit like an Oxon BCL.
Will anyone seriously suggest that it's a negative for one's legal career? Of course not.
Does this "prestige" translate to real tangible career value? Especially if you consider the 2 year opportunity cost? Unclear. There are so many other factors which potentially contribute to whether one's career succeeds or not.