The language for expressing constraints is what different, not the meaning. People are confused because they properly evaluate that you can do with this language what you can do with any other. But only up to a point of scale. Then the bugs that other languages make you introduce catch up with you. And you can't produce more software because you have to spend too much time fixing bugs of old software. In Escher, every circuit without valves is forever closed as design: for the same reason electrical circuits are rarely recalled. Did you ever wonder why that is?

Yes. All the functional programming language had the right idea (as you point out). But not the right grammar. Escher has 3 grammar rules (reflex, circuit and valve). All these other languages have much much more. That's the point.