It is fiendishly hard to disentangle cause from effect here. The sort of person to implement a dogfooded language is likely also the sort of person to care dee

It is fiendishly hard to disentangle cause from effect here. The sort of person to implement a dogfooded language is likely also the sort of person to care deeply about the quality of that language. It may be that just being in a position to use the language a lot (because you're implementing it) and to change that language (because you're the one building it) is enough to get the effect you've observed, but I wouldn't be at all surprised if you would only start down that path in the first place if you already had strong opinions about what a good language looks like.