Is it normal people delete comments?
Why do some people delete comments they don't like?
Last night there was a post that even warned users they would delete "mean comments" and I asked a question regarding why someone would even state that, which was of course deleted.
The only time I ever deleted another users comments was once when there was an unrelated off topic argument going on and I was sick of being notified every few minutes of it so I deleted the whole argument.
Other than that I see no reason to delete something, even if it goes against my opinion or is a troll comment.
If somebody cannot handle a variety of responses, they shouldn't have asked in the first place.