Why isn't std::initializer_list a language built-in?

Question

Why isn\'t std::initializer_list a core-language built-in?

It seems to me that it\'s quite an important feature of C++11 and yet it doesn\'t have its

Answer 1

It's not part of the core language because it can be implemented entirely in the library, just line operator new and operator delete. What advantage would there be in making compilers more complicated to build it in?