[lmm]

The language is the easy part. Getting tool support for your language change is the hard part. Getting the library ecosystem to adopt it is even harder.

I think that's why extremely flexible languages have seen limited adoption - if your language is more of a language construction kit where everyone can implement their own functionality, everyone has to implement their own tool support (or, more likely, live without any) and there's a limit to how far you can go with that. The best languages find the sweet spot where they give you enough flexibility to implement most reasonable programs, but are still constrained enough that tools can understand and work with all possible code.