Re: Itachi could have killed Obito...
Itachi lacked the ability to beat Obito.
Itachi lacks the footwork and agility to beat him, he's only fast in a straight line whereas Obito is keeping up with BM Naruto shown to be => Minato, the previous fastest character.
Genjutsu is out of the question, Obito knows all about Itachi and his abilities he wouldn't be stupid enough to get caught in that.
Itachi has nothing on Obito he hasn't got the stamina or chakra reserves to beat him at all.
To beat Obito alone you need to be as fast or faster than him and have a way to instantly kill him at close range.
Itachi has none of these things.
Itachi could use shadow clones, extremely easily dealt with, fireball anyone? Obito is an Uchiha, he doesn't just use Kamui.
Obito would take this in like 2 minutes, maybe less.
Unless Itachi used Susano'o which would only prolong the inevitable.
Gedo Mazo has no soul either, bye Susano'o.