They even mention it in the article. This is different as these are compsiting layers, not dom nodes shown in 3d. Compositing layers are an optimization technique.

I actually miss the 3D view. Anyone know why it was discontinued? I imagine it was simply too expensive in dev-hours to maintain compared to the benefit.

The first time I was telling a fellow .Net developer about the awesomeness of Firefox vs Internet Explorer, I thought the 3D view would blow his mind. It crashed instead.

Well, you can repeat the crashing experience with the Layers view in Chrome, then :)

Probably because chrome dev tools doesn't have that :)