They probably figured people who were willing to go through all the grinds to get this far, will just accept one more. I'm looking at the three ATMA's in my retainer thinking- yeah maybe I'll get the other 9 when I'm bored enough to do level-synced fates again just to turn them in plus the three I have, to free up the retainer space and be done with it. For people who have rejected the relic upgrade grind it's one additional reason not to do it, and for people who accepted it thus far- they know you aren't going to stop now.