I agree. If a 5wt rod works better with a 6wt line, it's a 6wt and should be labeled as such. If a 5wt line weighs as much as a 6wt, then call it a six weight! I guess it's the same reason a 2x4 is really 1-3/4 x 3-3/4, and a 9x12 rug is 8'6" by 11'6" !