Not from a coding perspective they aren’t. For this particular change, both the follower code in-game and on the website had to be changed. That means the core changes, and then two sets of API changes (the website uses the API to read from the game data files, and had to have its API updated to match the new in-game API). Believe it or not, the work for the followers was actually likely more taxing than the typical seasonal themes were individually. Incidentally, the length of time it took to code the follower changes would account for why we have such a small list of items that can be used for Emanation and also why the Broken Crown doesn’t operate the way we expect (it uses the character’s gem to determine the gem drop and not the follower’s gem in the crown).
If you think this was a “small” change, then go try coding something like even a seasonal theme and then tell me it was small with a straight face. I can guarantee you won’t be able to do that.