This is the least historically accurate game than the previous ones but even so I think its strong point is how it creates the worlds it puts us in, each one is a love letter to the era and I think from Renaissance Italy to recent Egypt there is a lot to rescue in this game franchise, being such an extensive saga it is logical that there are mistakes like Da Vinci meeting Ezio but I think I want to focus on how this game builds its world.
It's funny because when I think about this, I think about just how many people famous historically people must have met that we don't even know about. That is how I use to pass it off for the older AC games. I mean afterall Da vinci knows that Ezio is a part of a secret organization and I doubt he would go blabbing about it.
I mean we kind of see this happening in the dlc for brotherhood when Da vinci (IIRC) blabbed about the Apple of Eden and in order to protect him, and to ensure the apple didn't fall into the wrong hands, ezio wiped his mind.
But in later installments it can of became harder to do considering the usually big parts the protagnists played in historical moments.