Angry Grimace
Two cannibals are eating a clown. One turns to the other and says "does something taste funny to you?"
Um, no. They could have, if they wanted to. WOTC can do whatever the fuck they deem necessary for the health of the game and if that's sidestepping the mechanical theme of a particular set with a single, very much needed reprint, it's not going to kill anyone. Limiting themselves to things that fit mechanically and flavor-wise is unnecessarily prohibitive and, in turn, creates an increasingly unhealthy environment going forward. Such restrictions practically guarantee that a lot of cards that could use a reprint to alleviate cost concerns or supply issues will struggle to potentially find a place in new sets because those older cards might have some conflict with the story/mechanics/zodiac sign bullshit. This dogmatic insistence that everything in a set be singularly unified in design & flavor is the same lack of flexibility that's made the art in the sets too sterile.
BFZ/Oath wouldn't have been the ideal places for Inquisition of Kozilek but then they already fucked up by not putting it in the set that already had an original Zendikar block Eldrazi subtheme, MM2015. The absolute dearth of necessary reprints in recent sets has created a Modern environment that is becoming financially untenable for a lot of players and potential players.
They have a mono-black vampire tribe that serves Kozilek. There's also a black vampire guy that produces Eldrazi Spawn when he dies.
They could have reprinted it and didn't for developmental reasons, not lore ones.