Pretty sure the majority of the Aether/Primal servers aren't even congested for real, but SE decided to lock them anyways because of the amount of people that will be returning to the game just because of the expansion. It'll go back to normal in a week or two. I'm almost certain they just locked everything to prevent the servers from melting in case numbers spike too high. Not only that but also to try making people populate anything not balmung Crystal.