In Minagawa Uchiha's view, these tampered memories and perceptions could easily go wrong.
A person's thoughts constantly changed with their environment and circumstances. The same person could think differently from one moment to the next.
If this forcibly implanted perception matched reality, it was harmless enough. But if it conflicted significantly with reality, then as long as the target's understanding of things remained reasonably normal, they would likely notice the problem and correct themselves.
That way, the memories or perceptions forcibly altered by Kotoamatsukami could very well be broken through or overwritten by new perceptions.
Although Minagawa Uchiha looked down on Kotoamatsukami's crude method of altering perceptions, he did not mind recording this special technique that could reach deep into another person's subconscious.
Even if Minagawa Uchiha could not instantly output a massive amount of Dojutsu Power and enter someone else's consciousness, as long as he had the method, he could achieve the same effect by spending more time.
Besides, if an ordinary Mangekyō Sharingan lacked the power to achieve that, what about the Eternal Mangekyo Sharingan?
There was no doubt that it could. Just like Susanoo, an ordinary Mangekyō Sharingan could not reach the Complete Body stage, while the Eternal Mangekyo Sharingan could do so with ease.
Now that I think about it, even Obito Uchiha, who had half a White Zetsu body implanted, had never accomplished the feat of activating Susanoo with only one eye.
It was probably not that he did not want to use it, but that the Dojutsu Power output by a single Kamui Mangekyo Sharingan simply could not meet the conditions needed to activate Susanoo.
*But Uchiha Shisui managed it. Perhaps it was because his Kotoamatsukami Mangekyo Sharingan could amplify Dojutsu Power output, allowing Uchiha Shisui to accomplish the feat of activating Susanoo with