The Purple Elephant Problem happens something like this:
-I am reading about a book that's just come out or is coming out, and I notice people praising one aspect of it. (We will call this aspect a "purple elephant." Keep in mind, however, that purple elephants are not necessarily a "thing". More often they're a way of writing, a particular technique or style or tone, or a type of plot element or character or theme.)
-I think to myself, yeah, that purple elephant does sound really cool. I like reading books with purple elephants. Purple elephants are great!
-I realize that my book-to-be-published... does not have purple elephants in it. How about my works-in-progress? Ack, they don't have purple elephants either! And I can't see any way to insert purple elephants into them. Nor do I have any ideas that immediately come to mind that could involve purple elephants.
-I begin to despair ever having a successful writing career, given the dearth of purple elephants in my writing and my apparent inability to successfully include them in my books.
Thankfully, the despair phase generally doesn't last very long. Pretty soon I'm able to remind myself that there are many good books out there with absolutely no purple elephants at all. In fact, many of my favorite books are purple elephant-free. Thinking about the books on the bestsellers lists--why, the major of them have not a purple elephant to be seen!
I still have a lingering sense that my books would reach some higher pinnacle of excellence or enjoyment if only they had purple elephants. But I am somewhat comforted, at least enough not to throw all my WIPs in the garbage and sulk until I come up with a purple elephant-friendly idea.