Board Thread:Naruto Discussions/@comment-26993711-20160107221250/@comment-734582-20160108082939

Bocchi-chan wrote: Why didn't they have a squad of 100 Genjutsu users going through the World War knocking out all the Edo Tensei zombies? Because Genjutsu is a rare and difficult skill. Kurenai is Konoha's Genjutsu expert. She was dried off by Itachi in two seconds. Without (Mangekyou) sharingan, Genjutsu is difficult to achieve, with Sharingan it's still difficult to pull off.

Secondly, Genjutsu is not as reliable as say Taijutsu, in that a person can pretend to be under Genjutsu and strike back at the last second. Against someone with the Sharingan or Rinnegan, using Genjutsu can be straight up dangerous. Genjutsu specialists are already rare, using Genjutsu against someone with (to the ninja world) largely unknown powers is plain dangerous.