I would argue that DC and Marvel are not our world. Sure the land masses are the same, some of the countries are the same, and supposedly the government structures of these countries are similar, but the worlds do not feel like ours anymore.
Furthermore the points I made also apply to even those worlds even though I feel those worlds abandon the premise that they are like our world. Looping back with the OP in DC with Superman and Wonderwoman, or Marvel with the Fantastic Four, Avengers, X-Men, and Spider-Man it no longer feels like our world. If it did feel like our world we would say something even more Fantastic than those comics.