> Zeroing memory often means that buggy code will have consistent behavior; by definition it will not have correct behavior. And consistently incorrect behavior can be more difficult to track down.

I agree that using calloc should not be an excuse for writing sloppy initialization code. But in my experience, inconsistently incorrect behaviour (e.g. heisenbugs that tend to appear and disappear depending on the content of some random chunk of uninitialized memory that happens to be in an unfortunate state after malloc) are one of the hardest type of bugs to fix. It's the type of the bug that occasionally happens in production and typically can't be reproduced in a controlled manner in a development environment. I certainly prefer consistently incorrect behavior.