Board Thread:Versus Debates/@comment-142748-20150410212019/@comment-26127155-20150413060025

You are clearly mistaking people who can use genjutsu and genjutsu specialists. Madara and Sasuke are able to use genjutsu, but both tend to not use it during combat (due to not being comfortable using it) and tend to rely on ninjutsu throughout most of their battles. Only Sasuke, Shisui and maybe Kurenai come close to the level of genjutsu that Itachi uses on a regular basis.

Itachi's whole fighting style is based on his prowess with genjutsu. Itachi can use genjutsu to: immobilize opponent's, trick the opponent into thinking they have landed a decisive blow, cause his opponent to use their own jutsu on themselves, deal traumatic mental damage to his opponent, disguise his movements, and reverse other genjutsu used against himself. That is much more variety in the type of genjutsu that he has used compared to any other character in the series and Hashirama has no way, to be prepared for the barrage of genjutsu that he would have to face against Itachi Uchiha.