Why is there no language support in C++ for all C++ standard library type traits?

In C++ it is impossible to implement certain C++ standard library type traits without compiler intrinsics, using the C++ language only. Traits deal directly with C++ types. According to §17.6.1.3.2 freestanding implementations of the C++ standard library must implement <type_traits>. Doesn't this effectively mean that the C++ standard requires non-standard language extensions/compiler intrinsics from all compilers which support want to support freestanding C++ standard library implementations?

Why were such type traits allowed into the standard without support in the core language?