julia's package manager is quite modern (and very well designed relative to the mess that is either C++ or python, no experience in modern fortran for me), so something being external or in the core language is not as important as it is with other languages. this is also the same model as in for example, Rust or Javascript.
in fact, it appears to me that they intentionally made the core language with fewer amounts of intrinsics relative to other languages.
IMHO, one of the biggest advantages of Julia _is_ arrays.