It might be suggested that, without specific proof, sgraffito paiting is fun.
Acrylic for is not the best choice for sgraffito drawing (acrylic is not forgiving, even with gels) but the technique is fun if the paint is smeared onto the paper with the fingers, finger painting for older artists, and then scratched with any (sharp) object. Shallow art, and those few funny things probably just scratch the surface.
Scratching is one of nature's sweetest gratifications, and the one nearest at hand.
Michel De Montaigne: Today all the archaic imagery is gone.
How sgraffito cool things work is also a mystery. No, it's a philosophical joke.