Chronicles of Darkness is rightfully adverse to the possibility of placing certain gamelines "above" others in terms of how true their statements about the fundamental nature of the universe are, so they intentionally leave a lot of wiggle room, but this also ends up introducing a bunch of concerning implications
For example, in Mage: The Awakening, mages are stated to be partially linked to the Supernal Realms, a higher realm of existence filled with Platonic symbols that material reality is simply a pale reflection of, and the Imperial Mysteries sourcebook added rules outlining playing as Archmasters, mages which have strengthened their bond with the Supernal Realms to such a degree that they can physically enter it for a time and perform powerful spells that rewrite reality and even the simple act of becoming an Archmage rewrites history to a degree
This and other details like the lore of the Exarchs and other mages who had ascended to live permanently in the Supernal as transcendant wizard gods could've easily made it so WoD is basically a mage's world and all the other game lines were just living in it, so they threw in some lines mentioning that other categories of supernatural creatures (eg. vampires, werewolves, changelings, etc) have "sponsors" that archmages really don't want to risk pissing off because they are at or above their level
So could an archmaster cure someone's vampirism? Canonically, yes, but they won't because there's SOMETHING or mor likely MULTIPLE SOMETHINGS out there that, for unknown reasons, want to ensure that vampires and other supernatural nasties exist in any conceivable timeline and even the Exarchs, beings who got their current authority by KILLlNG GODS are hesitant to get on their bad side
A very reassuring thought
