Board Thread:Questions and Answers/@comment-6312663-20130302175900/@comment-11836-20161024213211

They were never meant to be the same universe, otherwise you would see Superman and Spider-Man together all the time. The Justice League wasn't involved with any big Marvel event, and how could they? DC already had two major Earths prior to Crisis of Infinite Earths, and neither of them could take place in the Marvel universe. The differences between both versions of Atlantis, whether or not Dracula exists as a real person, how major threats like Galactus and Godzilla were never mentioned by the likes of Batman, etc.

Also, I don't see how one-shot comics being alternate universes are a bad thing, but then again you want to believe in a single universe where Superman exists alongside Gladiator, Sentry, and Blue Marvel and nobody seems to notice there are a lot of Superman-like beings that would make Lex Luthor want to jump off into a volcano.