Being an editor is an eye-opening experience for an author. You come to realize editors see many stories they'd like to publish but non-artistic sensibilities, like issue balance, intrude on the selection process. You can't have an issue of all vampire stories, for example. Unless it was a themed issue... Hhm... I digress.
The point is, many stories are publishable and don't make the cut.
Being a writer is hard. But, it's worth it, right? :)
Good luck with your writing endeavors!