Yes! That was more or less my point. But since we're all confused anyways: Do you have an example for a real 2D game engine? with "game structure" as you call it.
Godot has a 2D renderer and physics option, Defold is 2D by default, Game Maker Studio, Cocos2d, Corona, Construct, Phaser.io, Buildbox, Gamesalad, Stencyl, Clickteam Fusion
Unity is very capable of 2d games too and provides a lot of game structure and so do many other engines (I want to mention Heaps.io because it’s awesome).
Commenting because noone else has mentioned it; I've been enjoying love2d[1] because it paves over all the annoying technical issues I might run into, and exposes it all in a nice lua api[2].
