Here's the specification of calloc from the ISO standard:
18.104.22.168 The calloc function
void *calloc(size_t nmemb, size_t size);
The calloc function allocates space for an array of nmemb objects, each of whose size is size. The space is initialized to all bits zero.
The calloc function returns either a null pointer or a pointer to the allocated space.
That specification gives the implementation exactly two options: return NULL, or return a pointer to a block of sufficient size.
The article says you should use calloc because it provides these optimizations. I am saying no, that's goofy, because it is not specced to provide these optimizations.