Quote Originally Posted by Vickii View Post
I think comes down to spoilers
SHB making a big deal about the identity of the exarch for it only to be a minor character that the majority of players didn’t meet. By making those mandatory just before his reveal he’s fresh in everyone’s mind and no one is going to complain they didn’t get the full benefit of the plot because they didn’t do some old level 50 quests.
It's not even just so people get that story significance (although that was probably a good enough reason on its own), but because certain events in 5.3 can't chronologically happen without CT happening first. Before that point, it helped your story comprehension but it wasn't actually necessary.

Also you don't do it "just before the reveal" unless you were one of the people who had previously reached 5.3 without playing CT. For new players, CT is now required at its intended point in the story in post-ARR.