I would not immediately disagree, however Woj that most Mantles have been around since the beginning complicates things a bit if you don't consider the source of said mantles, specifically those whose source is known, are directly broken down pieces of the Mothers greater power.
Their are a few ways to attempt to broach and reconcile the subject though, mostly dependent on some leveraging of facts vs theory....
First if you consider woj angels are too... and I forget the precise wording now but whole for Nemesis to mess with, with the idea Angels are Celestial stars and we are on the star 'Gaia' in a cabbalistic manor, giving us a direct shadow of our own reality and then point out MW and indeed the broken down portions in the Queen and Lady are brought inside reality in order to create a balance, which takes it away from our Dark Star/Planetoid.(astrologically and scientifically named Nemesis...) Then consider what Nemesis CAN mess with has consistently been mantles that exist inside our Star and source directly from the alloy of balance between and you could say all the mantles we know of are broken down pieces of the identity of our own reality/star made manifest genus loci style. And certain angels we have seen are those who came from the stars to earth and formed a true avatar or otherwise overwrote the star via starborn effect, becoming it in truth. (Hence Uriel's dual existence and ability to transubstantiate, as his own self)
Or.. We could take the "mantle of power" literally and point out every being we know of that is a Mantle is also... while not necessarily not the original being, as Cat Sith is, But Not an original representation for said power, or holder of said positioning.(some divergence here from Eldest Mantles to every other Mantle, Eldest Mantles imo apply the 9 psyche's of the consciousness and disperse them, giving that mythical shadow/devil inside us all a barrier between it and the queens, which are just another barrier of course) So those things sacrificed or otherwise killed that are connected to reality become positions of power, where-in the spirit of said being does not pass with it's consciousness as it's somehow stopped from fusing into an afterlife existence.... Which may cause such disembodied beings as outsiders? things not tied to Mantle form can still try to effect reality, but it's less structured in it's attempted possession and it's inherent results... fyi reality champions choice, and Mantles don't take conscious choice away, they restructure it based on your own choices, while making the mantle replace your ID, But notice despite it all Molly is still able to choose as far as within the mantles authority? Looking for a new source of fighters was quite an elective choice... I theorize it has to do with the mantle changing as it subsumes your soul/identity into it.
Other stuff... what were we talking about again?