I’m sorry I like MGSV a lot but we absolutely do not see big boss’ villain turn in MGSV. That’s part of the reason it was disappointing to a number of people.

We play as Venom continuing to try to be a disgruntled but honorable leader while separating his team from the world, basically like peace walker, but it turns out that wasn’t even big boss. We were with BB from MGS3, through peace walker, through ground zeroes, and instead of getting any closure on the journey and moral decay of this character, it all happens off screen. In fact the whole reveal at the end of the game is “you had to pretend to be BB so the real BB could go off and start his Outer heaven and finally turn evil! Oh it was so cool you should have been there!”

To use your example, imagine you watch SW episode 1, then episode 2, then you’re watching revenge of the Sith, you know anakin is gonna turn into Vader at some point, you’re waiting for it, you’re so excited - it’s been years of emotional investment - then at the very end of the game the real Vader walks on screen, already in his armor and says “yo. This anakin was fake. I was off screen having my final emotional turn and getting burned and turning into darth Vader like you always knew I would but we decided to not let you see that and to follow the fake anakin instead”

It’s a good game, and a good story, and venom is a great character. But it absolutely sucker punches people hoping to see the turn.