​Amen...   it was rarely useful.   I always found realloc to one of the part I could never trust.  I do remember  what you got back from any of the malloc calls could vary widely.  Particularly pre-ANSI C and working on non-UNIX systems.

Malloc in general was always a tarbaby because there were (are) so many implementations "in the wild."   I used to advise our application people to create something that was application specific and then call the local malloc under the covers, but the chances that a general malloc implementation would be optimal for your code was low.​

Clem