Yeah, I see what you're saying. But there's really a bit more to it for Marvel. They had Franklin dreaming up everyone's history. So ideally it would be identical to what was before Secret Wars (minus the transplants), but it doesn't necessarily HAVE to be identical.
For example, I expect the new Punisher series will feature a Frank Castle who is a veteran Marine of non-specific Middle Eastern conflicts, not Vietnam. That way he's not in his seventies (though the FrankenPunisher thing already took care of that... painfully badly).
So I guess I'm saying we don't know the past is canon unless it's revealed anew as canon.