Dude, just suck it up. It's just a deleted post, and mods delete posts in bulk sometimes. Having to include an explanation for each of them would be ridiculously time-consuming. Most likely the post was insubstantial or off-topic. I've had plenty of posts deleted, and I've never contested any of them that I can remember.
Since the title of this thread is so grammatically warped, my guess is that your post was a shitpost that got reported as such. The rest of what you wrote isn't bad, so I'm just guessing here. It'd be nice if you showed what got deleted.
And admins, if possible could flag a post and message the user to delete it himself.
Yeah, no. Not a good idea.