He can though. With full intel and nothing holding him back, you really think Itachi is going to sit and easily allow Kabuto to execute something like Tayuyas genjutsu, for example? He stated Oral Rebirth was difficult to detect, but at the same time was nearly blind. He got caught by Kabutos while dropping his guard completely, and putting all his focus on initiating Izanami. Won't be so easy this time around. Orochimaru's poison gas didn't make it's way through susano'o shroud [
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]. Kage Bunshins can be immediately countered with Explosive/Crow Bunshin, among other methods. Itachi is the more proficient bunshin user anyways; even Kabuto didn't detect it's immediate use.
The fact of the matter is, Itachi had to hold back immensely. No disputing that. A lot of the scenerios he was caught up in would of never occured in the first place, especially with given intel on it. Catching Kabuto with Totsuka really isn't that much of a stretch, considering Itachi already cannonically was able to create an opening for it. Added to the fact that I don't even think Kabuto has intel on it, unless you can prove otherwise.
In that case, Yata repels all of the webs right back at Kabuto, while Totsuka sweeps the bones. Or alternatively, Itachi
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his way through the webs with Yata Mirror in front of him, before the bones reach him. Magnatamas/ bunshins handle the clones. And I see no reason why susano'o would drop in it's lower stages when used in tandem with Amaterasu.