It may not do a lot in terms of driving our personal story forward, but it makes a huge impact on world politics. It completely rewrites the state of Garlemald's empire, making it critical that it happens at that point in time so that further MSQ can take place in that altered state. It's not something you can just put to one side and do later.
Maybe it could have been written differently back at the beginning, but it's too crucial to remove now.