Why are cinnamon rolls marketed upside down?

Nope—the upside down thing is for sticky buns, which aren’t the same as cinnamon rolls. A sticky bun has a thicker filling, with more sugar (often with nuts or raisins as well)—it cooks into a syrupy consistency at the bottom of the pan...which is why those rolls are flipped after baking.

Cinnamon rolls have a drier filling; they’re baked rightside up then usually frosted or glazed.