Read this article about the .318 Westley Richards the other day and immediately thought of the parallels with the 6.5 Creedmoor. Its not that the 6.5 Creedmoor is a bad cartridge, its just that it shouldn't be used in hunting situations in which it was never intended...like elk past 300 yards.
Bit of a long read, sorry in advance.
"...the .318 quickly became immensely popular in Africa. The 250 grain soft nosed bullets proved extremely effective and penetrative on game, while the solids if properly placed could down an elephant with a brain shot. W. D. M. ('Karamojo') Bell, one of the greatest of the old ivory hunters, used the .318 extensively. Indeed, from my readings, it seems as though he used the .318 at least as much (if not more) than the Rigby 7mm/.275 that he is most famed for using. HOWEVER just because Bell shot thousands of elephant with the .318 (and calibres like it), and lived to die of old age, does NOT make the .318 an elephant gun! This was a partial explanation for the eventual downfall of the .318. It became very popular extremely quickly, and is certainly one of those well balanced cartridges that performs out of all proportion to its size and paper ballistics. It was so effective that hunters started to use it against large, thick-skinned, dangerous game animals for which it was never intended. Well placed it would do the trick, but it was found wanting when things went wrong and a charge had to be stopped. Westley Richards themselves would tell you that the .318 was not designed for such stunts; that is what they designed their .425 for, and they would happily sell you one for hunting the big stuff that bit back. Hunters still used their .318's for dangerous game, though, and continued to be knocked about accordingly at times. A certain backlash was inevitable, but the .318 was still so splendidly effective against soft- skinned game that the process was more of a placing of things into perspective. Good as the .318 was, it became recognised that it did in fact have limitations after all, and that one would be well advised to take at least a .375 against the more malevolent species." - Charlie Haley, AfricaHunting.com
Substitute ".318 Westley Richards" for "6.5 Creedmoor" and "elephant" for "elk" and its the same argument.
So when enough people lose enough animals shot with the 6.5 ManBun, the sun will set on this cartridges use on animals on which it was never intended....everything larger than whitetail deer. I could also point out that it was actually designed to punch holes in paper at long range out of an AR platform, but I'll give it a bit more credit than that.