The reason is that defaults are powerful. Languages tend to have an owner in a position to declare a default for a language. No one is in a position to declare a default for polygot environments.
This also explains why the only places where these polyglot systems seem to be really common is at giant companies, where they have the power to enforce that stuff is interoperable. If your employer tells you to do extra work to make sure that your package can be used by others in the company, you're going to do it, but if you're working on some personal open source project and have the luxury of deciding what to prioritize, most people are generally not going to be spending time on figuring out polyglot build systems and will just use whatever's easiest, which will generally be whatever the language's default is.
saghm|3 years ago
sanderjd|3 years ago