Deep methods are a vast improvement over classical computer vision techniques. Classical techniques can be thought of as a function of the raw pixel data. Deep learning techniques understands the context and are more likely to get segment how a human might segment.

spectral matting, as I understand it, is used for subject/foreground and background separation.

It's easy to say something is better, but good computer graphics and computer vision papers compare themselves to the state of the art.

This is ignoring all that and comparing itself to the most manual method possible. This also happens sometimes and is more of a marketing stunt to people who don't follow current research.