Personally I don't like the idea of cosmology splits at all. I don't think we should split anything that isn't a canonical difference
Although I dislike splits, I feel like sometimes it can be a better approach than repeating the same discussions time and time again because of inconsistencies.
Marvel doesn't has a solid cosmology that is unchanging, it's always changing and being retconned, sometimes for bigger stuff, other times it becomes more limited. There are times the universe is portrayed with infinities upon infinities, and other times in which it being finite is an important plot point.
Naturally, some attempts have been made to unify some cosmologies, but even those attempts aren't absolute and they themselves can have their elements set in levels that were not indented originally.
Because saying there's no "canonical difference" isn't really right, the difference in canons is very clear. The only thing that isn't official is the names and "authors related to X cosmology", those are things that are decided by each fan, but knowing that different writers portray marvel and its characters differently is a very clear thing that has been recognized many times, going beyond even singular writers even into editorial. There were times in which Marvel has an editorial that is very certain about a certain lore that needs to be followed, and other times in which that isn't the case.
If someone attempts to make a singular "Marvel cosmology" that is impossible because of inconsistencies, then choices need to be made. Deciding what it a retcon or not, where each thing is in the cosmological hierarchy, which cosmic being is above the other, these are things that are all over the place so even deciding in one over the other is already making a personal choice.
I would say that the cosmology split is a way of at least acknowledging all these different inconsistent point of views as valid to their own, and although some elements are incorporated by others, it's not done without some level of retconning for example.
Naturally, making such choices would need a lot of research and nuanced discussion on Marvel, but I wouldn't say it's something that is absurd, just one of the many consequences of having a widely contradictory work.