I agree that it would be rare for a memset() used for initialization to be removed, but this is a good recent paper that gives lots of examples of when stores are eliminated in practice:
Dead Store Elimination (Still) Considered Harmful
Dead Store Elimination (Still) Considered Harmful
For the sake of argument, can you show me some example code where it would be conforming to remove a memset() call? Preferably a realistic example and not a Google'd copypasta. Because it's all too easy to just regurgitate things you heard and think you understood, but no so easy to demonstrate it yourself.