Most memory safe languages lack enough power to implement their own runtime systems (except in an extremely inefficient way), because so many languages ultimate

Most memory safe languages lack enough power to implement their own runtime systems (except in an extremely inefficient way), because so many languages ultimately rely on an implementation in another unsafe language that has access to machine capabilities. Implementing the runtime system in the language itself is a black art that requires an unsafe dialect or extension. E.g. all the Java-in-Java VMs sneak dialect features in through intrinsic classes like "Pointer" and such that are recognized by their own extended compilers.