This is a good point, but it's important to be clear about it. There is no universally superior language. There are a number of competing factors which means that optimizing for one sacrifices others. So instead of a single point in space that maximizes all of them, there is instead a volume bounded by a curve and going farther in one direction requires lower values on other axes.

But, there is a lot of space nowhere near that trade-off optimizing boundary. You can absolutely make languages worse in ways that are strictly negative for all users. For historical reasons, all languages contain some amount of that dead weight. So the absense of a perfect language does not imply that all existing languages are right at the edge of the optimizing boundary.