Personally I find “All the Sith” to be one of the few interesting concepts this film has going for it, and the only thing that justifies Palpatine’s return in this trilogy. Him being a conglomerate of powerful evil spirits makes the idea that he can just come back from the dead more digestible, and having the ultimate final threat be the living manifestation of the Sith being banished by the spirits of the Jedi is atleast enough to give this movie the feeling of a saga wide finale, instead of just being that one old guy from the other movies that has nothing to do with this trilogy being shoehorned in at the last second (I mean he still is, but this explanation at least justifies his inclusion in a more meaningful way).
Losing this aspect of the film would make Palpatine’s return unbearable for me, I’m not being hyperbolic. I don’t mind that it doesn’t gel perfectly with ‘Rey Palpatine’, it’s not really a plot hole, just two ideas that don’t match completely well but don’t necessairly need to.