100% that gnome
I think most of those adventures could have been set on a single world (Ansalon is a continent that's having a war, which is separate from the damned continent/archipelago that is Ravenloft, which has areas from the rest of the world pulled there by the Dark Powers, etc.), but that ship sailed a long time ago.I suppose if D&D focused on a single world rather than multiple, you could afford such specialization. But that comes at the cost of never getting Ravenloft, Spelljammer or Dragonlance. But I can't see them ever supporting settings when that level of granularity again.
I cannot imagine the drama if WotC had announced that all of the D&D worlds were actually one planet, despite it having functionally little impact for most games. Just make all of the "the entire world is affected by X" into "the entire continent is affected by X," which is still a pretty big deal, and you can suddenly have the prospect of characters setting sail from Waterdeep and getting shipwrecked up on the magic-starved continent of Athas, where escaping is going to be very, very difficult.