Is there a reason why there is still no group chat option?

People have been asking for this feature for a very long time. If there is an iMessage group chat option then surely it should be easy enough to add the same thing to the others. Many AU writers, including myself, use the group chat feature to write stories. In my opinion, it is not a big hassle to add this feature and should be fairly easy to get done already. Unless there is a specific reason we are not getting a group chat feature.