I was mostly considering the lore up to MGS4 but I suppose that is true, I guess Im not a fan of the MGS5 retcons but I will admit that there is an element of tragedy in the fact that Zero wanted to bury the hatchet with Big Boss, likely after undergoing a "Are we the baddies" style moment (alongside with knowing his time with a functional brain is limited and Skullface is playing both of them). It does make me wonder what would have happened had John just miraculously just woke up right when Zero asked him to and he believed and accepted the olive branch. Maybe they would have a mature discussion over what they are doing is truly The Boss's will or not and, well, what to do now that Zero's time as a true man capable of thought and reason is fleeing.
New Info isn't retcon in the traditional sense, from Big Bosses perspective, everything he said at the end of MGS4 was true, he never learned the truth, and no one told him, the only men who really knew everything were Ocelot, and Kaz, and Kaz who had a very very hair trigger on perceived betrayal due to his youth, flipped on Big Boss for pulling the Venom bullshit switcharoo on him, which is fair, imagine you'd literally get tortured and die for a guy, but in reality he abandoned you to go start his REAL Army, and left you with some weird brainwashed stitched up doppleganger.
and by then Big Boss was full in Zanzibar Land his last conscious moments are fighting his own clone and then waking up 20 years later..
I do love the central theme of MGS though, and its CONTROL, and it can best be exemplified by the main people being CONTROLLED.
The Boss is the first person that is controlled, the Philosophers use her to do all sorts of shit, and they control her actions, and even take away her newborn son
Then, Big Boss/John is the one who everyone wants to control, Cipher wants him to do this that and the other, be their face, its a control of both identity and purpose
Venom is the next layer, they control his thoughts, his identity and his emotions,
Finally, the True puppet masters step forth, and they have their next level of control over their target, Solid Snake, who they control like a weapon unlike the rest before him, he has no context for the things he does, he simply takes out The Patriots many enemies, Venom, Big Boss, Foxhound..
then they really up their game, Raiden is the next level on that, where they use the data from Solid to try and "make" anyone into a Solid Snake, they control his history and his future, they have so perfected their control they can tell Raiden to his face that he will fight and kill Solidus, the only impediment to their plans, and that they own him, and since they made sure he would do it by hand picking an ex-Solidus child solider and running every aspect of his life for a decade, he does just that.
and Finally, they put all this into work and put it into action to control Conflict itself, and everyone on the battlefield, down to what they feel, think and what they do, who they fight, why they fight, everything.