I saw that on Tumblr. It's fanfic. Lol
That person got mixed up. The sharingan doesn't ingrain memories, it's a measure of how much trauma an Uchiha has endured. In Itachi's case:
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It doesn't literally burn memories into a person's mind. A person remembers what they see whether sharingan is on or not. Remembering what you did has nothing to do with being an Uchiha. No one in NV (bar Gai lol) has short-term memory the last time I checked.
Itachi was stated to have his sharingan always on in Akatsuki because he was keeping his guard up. Akatsuki are known to kill their own partners. He didn't know if one of those members would come for his life or not, so he always was ready just in case. However, it is a known fact that out of all the pairs, Itachi and Kisame were on the best terms with each other.
They never went out for pocky. :|
That and Itachi was alone for a good while in Akatsuki. He joined at age 13, was paired with Orochimaru and made him leave the same day. Then, he was alone until he was 17 and paired with Kisame. And then, he died at age 21. He only had a partner for 4 of the 8 years he was in the organization.
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All pages for Databook 4 (Raw):
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Only took a day to get leaked. Now to wait for someone to translate all of that.
Especially all of this-
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