Question about platforms

[QuartzTS]

Excuse me, can anybody tell me why platforms use Shape3D nodes? Also I noticed that the platform scene objects that hold other objects (like monitors) have the same child nodes as the nodes inside the scenes itself (I think that's why they're colored yellow)

[Caverns4]

The answer as to why they use a "Shape3D" node is that they don't. I don't know why they're called Shape 3D, but 3D nodes are denoted by a pinkish-red color and that's blue, therefore 2D. If you want to be sure, click on the Shape3D and look in the inspector. It's probably a CollisionShape2D the originally creator made a mistake naming or something and it it just never got caught.
As for why the Platform and its children are yellow, I'm not sure, but it likely because they're a PackedScene with editable children enabled on right click?