For the same reason the audio failed when he basically called Perry a chickenshit. The same reason that they dismiss straw polls when he wins. The same reason why they call him "crazy uncle Ron" one minute but then agree with him the next. The same reason why the keep repeating that he can't win but then remove polls that obviously show him winning.
There are plenty of articles that admit he's a serious contender, I don't know why some "reporters" are still in denial at this point. I don't even care about their ignorance anymore, all he can do is just keep plugging away, at least he is defending himself a but more aggressively these days.