Its just hardcore Itachi fapboys no letting go because deep down they know that Itachi has no purpose in the manga anymore.
In regards of the yata/totsuka thing it is definitely a hyperbole. Whilst the databook is writted by Kishi and is therefore canon there are still anomalies within it. So examples include Kakuzu's earth grudge fear being impenetrable and chiyo's puppet chakra shield being able to block anything. Some others are Kisame in shark-fusion-mode being stated as having no weakness and Haku's ice mirrors being unbeatable.
We need to take things with a pinch of salt, but this seems impossible for fanboys. They cling to every mention of Itachi and twist and manipulate it to there favour. Itachi-fanboyism seems to me a new fad infecting the base, just laugh at them and move on.