If we had a universal interpreter for all available features of programming languages we could use a specializer to generate compilers for all languages. We could simply use any language as source (or input) and any platform as target (output).
We could all write in our favorite programming language to add features to that universal interpreter because the base Abstract Syntax Tree (used by the universal interpreter) could be a target of our favorite programming language. On top of that, you could view the 'source code' of the universal interpreter in any language because the 'source code' of that universal interpreter is actually an AST.
Despite programmers having these sort of ideas for more than 40 years most of us still seem to think that we need to choose a specific textual representation and appropriate interpreter (or specialized interpreter called compiler).
I don't get why that is. There are so much programmers around and most programmers are really passionate about their ability to create. I don't understand why we fight about different programming languages, to me they seem like a different view on the same AST.
Why are we all not using the same base as a library from which we can pick language features?