But you forgot that Itachi has pretty hair is a vapid awesome power fantasy so he takes the leadactually you mean obito.
Hes the one who made kakashi the way he is (and by extension naruto/sasuke)
Hes the one who killed naruto's parents making naruto the way he is (and by extension sasuke due to building distrust as fallout of said deaths)
He's the one who made sasuke the way he is by killing the clan
He's the one who pushed sasuke further into darkness
He's the one who started the war
He's the one who saved them both multiple times
Hes the one who manipulated nagato
He's the one that created the akatsuki
I can go on and on. But its clear from jump that obito is the most pivotal villain in the entire series and is the one that created and pushed the plot.