After WandaVision and The Falcon and The Winter Soldier dealt with the post-Endgame reality of the MCU, Loki has been exploring the consequences of the path chosen to get there. Ever since 2019 that the discussion of what time travel rules within the MCU both validate and negate has never really gone away, but what was made exceedingly clear is that any changes made while in the past would create alternate realities. What this entailed, and the number of diverging timelines the Avengers created out of their time heist, has been another discussion in and of itself. It’s been hard to come up with a unifying theory that managed to explain all loose ends and define what constituted a major change to the timeline because, for all we know, a seemingly small detail as Clint Barton retrieving a baseball mint from this home in the past could trigger World War III in the future. But, two years on, Loki has seemingly managed to put all those doubts to rest by introducing us to the TVA.
It could have gone one of three ways. If the choice were to be to simply introduce a type of randomness regarding timeline interference that allowed for anything to happen, at any time, for no reason at all, you would obviously open up a lot of narrative possibilities. But by doing so, the emotional impact would be lessened as dumb luck would be the reason for anything, everything, to happen. On the other hand, by clearly defining said rules as being something woven into the fabric of how the universe works, just as physics or chemistry are in ours, it would ground the timeline interference concept but, at the same time, it would leave little room for that extra pinch of intrigue. Reality would become predictable as the universe would not change its modus operandis, it would not pick sides according to the situation, it would not trick you in order to come out on top.
So what Marvel Studios did was probably make the best decision they could have made when focusing on future drama within the MCU. With the TVA, an organization with apparently very strict rules in terms of what it does and does not allow to occur on each timeline, but still run by someone with its own agenda, Marvel Studios has managed to give itself the necessary leeway both moving forward and in explaining past narrative choices. They can easily delete or keep individual timelines when that helps with the story they want to tell, diminishing the number of loose ends that could have come and bite them in the ass later on. These decisions can either be pretty strict by following the will, code, and interests of whoever is in charge of the TVA and/or its tech, or, at the same time, can become pretty random and unexpected if that power is spread around through multiple factions down the line.
As we approach Loki‘s season finale, The Man in the Castle is about to be revealed. With him, his agenda and his own endgame, the future of the MCU will probably enter a new phase in terms of what is and what is not allowed to continue existing.