[int_19h]

It stems from B, because it didn't have either pointers or arrays on the type level. Declaring an array allocated the storage, but the variable itself was still a word-typed pointer to said array. In fact, you could even reassign it!

   foo(a) {
      return(&a[1]);
   }
   bar() { 
      auto a[10];
      a = foo(a);
   }

The decaying system made it mostly work with minimal changes in C.