I don't think all people tell others of the pain or feeling of loss of control as a way of being a 'horror story', sometimes it is to give information, to help prepare their friend, or to let them know it can be really painful or an extraordinary experience but you can get through it.

Some people do like drama and oversharing, and birth is just one of the ways in which they express these. And some people have alot of fear around birth, it is part of the industry of birth, fear is propogated so people keep buying up the merchandise.