When you reply to someone, it would help if it added the name of the person you're replying to at the beginning. I'd assume it would grab the name from the post that you're replying to.
You can type it in manually. But it would seem to be easier for the system to automatically add it, and for someone to delete it it they want. I'm not sure why would anyone would want to delete the name of the person they're replying to, though.
