There's no reason the standard template library (basically Generic container types and their support) should require compiler support in C++. However C++ programmers tend (incorrectly) to use the abbreviation STL to mean the entire standard library for their language. So this can result in talking at cross purposes.

Thus while your parent may have meant that types like std::unordered_map shouldn't be magic, it's true that for example you can't implement atomics from the standard library usefully without help from the vendor.