But Itachi was notoriously skilled in genjutsu outside of Sharingan too. So its unfair to make that comparison.Not all of them. For instance, Sasuke has put all the biju under genjutsu without looking at each of them, with a single glance. Itachi also used genjutsu with just a finger, without any eye contact.
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As for the Tailed Beast thing he actually had to make eye contact with them. And again we can't compare Bijuu to humans. Especially when Bijuu's are known to be easily sealed by the Rinne no Jutsu. There could be something special about that scenario