I have to disagree. Only in the rare case of potentially dangerous people with no way to hunt you down does ghosting seem appropriate. Everywhere else it strikes me as irresponsible, callous, and potentially damaging to the ghost's reputation.
Rejection does not have to be harsh. "I don't think we're a good fit," is easy to say, hard to argue with, and provides no concrete mistake for the rejected party to feel bad about, if that's something you want to avoid. (Personally, at least after sufficient time has passed, I prefer someone actually tell me what they didn't like, but not everyone feels safe doing that.)
