Who says K. Rool is a shoo-in? I can't recall anyone saying that for quite some time. He seems to be viewed as likely at best, impossible at worst, from what I can tell.
Dark Pit, on the other hand, I have heard people call a shoo-in. Naturally, I dislike Dark Pit for this.
I suppose one never forgets, I am quite hypocritical. I always assert that the fans of a character should never influence your decision regarding the character... but I cannot help it in regards to King K. Rool.
I understand your feelings though, when people fail to recognize something is not absolute, I am adverse to the notion. It happens to me with Ice Climbers, Rhythm Heaven representative, and Shulk, of course. It also namely happened with Toon Link's non-inclusion, Rosalina is too late, Pokemon Trainer's return, Phantom as an assist, and Chrom.
Of course that is not entirely relevant as I do the same thing with characters such as: Wolf, Ridley, or Mewtwo.
I am glad that people are recognizing Dark Pit's viability, I have no idea is advocating for "shoe-in" Pittoo. It is not Golden, it is not BluePikmin, and it is most certainly not I. But those are the only Dark Pit supporters that I am aware of aside from FrostWraith (who is skeptical) and Kage (which is probably the person you are referring to). I am fairly certain that Weeman is being facetious, as I occasionally do.
In FACT, that is precisely why I support Dark Pit. All of the fallacious, "he is a costume because arbitration, all of this evidence means nothing... do not call me biased, they are the SAME character." The signs point to another obvious roster alteration yet those who were to blind to discern fact from reality before are STILL blind.