You don’t need a mechanism to point out a fact contradicts an assumption, eg, our measurements show non-uniform mass at virtually all scales (including billions of light years). There simply is no observable scale with uniform mass.
Obviously there’s some mechanism which causes that, but the mere existence of multi-billion light year structures invalidates the modeling assumption — that assumption doesn’t correspond to reality.
yeah the ~1b ly nonuniformity is pretty much there. the ~10b ly uniformity is still early days but looking more and more likely as more data roll in (unless there is a systematic problem)
Obviously there’s some mechanism which causes that, but the mere existence of multi-billion light year structures invalidates the modeling assumption — that assumption doesn’t correspond to reality.