It’s one of the cruel truths of the industry that a small well-liked company can say, “we like eating babies,” and fans will ask them to explain it and probably understand the context.
But WotC says “5.5” in one context and its torches and pitchforks all around.
And it's hard, because there are so many new staff there who probably didn't even realize why this was an issue. It's a game so big and with so much history, that the numbering seriously matters.