Layers are more efficient within the context of screen real estate. And for comping. in most situations that I encounter...
...and, of course, all IMHO. No other DAW had anything like it. I know some prefer lanes, but I'm glad to see more people coming out on the side of layers because I believe the best way forward is to support both lanes and layers, just like there are two ways of handling envelopes.
Please, bring back layers. Ad a few fixes for lanes too...