No, that title is not the beginning of a really bad joke (although it easily could be ^-^), it's the way you need to think of your stories. In plain language, that means you don't have to worry about using a stock plot such as Boy meets Girl, Boy falls for Girl, Boy and Girl start dating, Boy and Girl have a misunderstanding, Boy and Girl reconcile and ride off into the sunset. If you think about it, that is the basic plot-line of almost every RomCom on the market. The reason is that people like clichés. They like being able to predict how the story is going to end. Which is why you always know what you're going to get when you go to the movies or the bookstore and walk into a specific genre section. In fact, you can break almost every genre down into one, basic plot:
There's a Big Bad who is oppressing the people. An unlikely Hero rises from the ashes, gathers a group of friends, confronts the Big Bad and loses, regroups, receives training from his Mentor, the Mentor dies and the Hero has to choose his own path, the Hero goes on a character building adventure, Hero faces down the Big Bad, wins and gets the Girl.
Someone dies, an unorthodox Detective goes on the case, they make several false deductions before discovering who the Very Unlikely Killer is at the last minute, there's a fight or struggle but the Detective catches the Killer who is brought to justice while the Detective gets the Girl.
A Group or Individual finds themselves on the wrong side of a Spooky/Creepy Entity, the Group/Individual tries to find the Entity to stop it and several people are killed along the way in gruesome circumstances, they confront the Entity and either a) vanquish it or b) everybody dies but the Entity still disappears/dies/becomes dormant.
Even Literary stories have a generic outline, and the honest truth is that there is NO SUCH THING AS AN ORIGINAL STORY. Any and every story you might ever want to tell has already been told. The trick is to figure out how to tell your story in a new way.
New and innovative storytelling is the reason people return to the same genre. That's where The Box comes in. The stock plot is what you'll find inside The Box right alongside your stock characters. Every Fantasy story has a Hero, a Mentor, a Love Interest, a Villain, and an Evil Lieutenant; it's your job to think OUTSIDE of The Box in order to make your story and characters different and memorable.
Stock plots are important, but if that's all they are, they'll fall flatter than your Box being sat on by an elephant.