Going into any long-running comic, I understand I might not fully grasp the subtle character dynamics, that some jokes will go over my head, and certain subplots will leave me curious. But that doesn't mean the writer should neglect new readers when it comes to such things. One or two lines of exposition will do the trick.
Now, the story: yes, we're coming into the "eighth season," but this is a book with a beginning, middle and end. Did the characters and world exist beforehand? Yes. Will their stories continue afterward? Yes. But the volume itself should feel like a complete, satisfying story. Anyone should be able to pick it up, understand what's going on and enjoy it. That's the point. This missed the point.