Modules and libraries are not part of the language

Java,for example, can't have proper generics because at the bytecode level (the "real" Java) they are not supported, it can't have static constructors because it would break inheritance and they had to come up with static blocks, it has no support for static methods with the same signature of an instance method, because the call syntax doesn't differentiate a call to a static method from a call to an instance method, so the compiler can't tell which method is being called, etc. etc.

These are all consequences of the original choices taken 25 years ago when they designed the bytecode and the sintactic sugar over the bytecode, that still live with us today