As I said a couple of my posts back, JLA Incarnations #5 came really close to retelling Crisis from a single Earth post-Crisis perspective. More generally, the main reason I bring it up is that it can be used to resolve the New Golden Age timeline for the JSA and related characters, without having to delve into creating some new event to explain a time skip for the All-Star Squadron and related characters. (Would it be easier to just restore the JSA's Earth 2 origins? Yes; but that ship has already sailed where the New Golden Age timeline is concerned.)
That said, I'm not arguing that CoIE should be recast solely in terms of a single Earth and a single timeline; I'm fine with, say, Earth 3, Earth 6, Earth D, and Earth X still being treated as separate Earths in the revised take on the Crisis. I'm just saying that a remarkably large amount of it can be recast as different eras instead of different worlds, and that there's precedent for doing so.