Yep, exactly. If a story spends close to 2,000 pages leading the reader into dead ends (Renly, Stannis, Caitlyn, probably Dorne... too many to list, really) or circular nothingness (Sansa, Arya, a few others), there's something fundamentally wrong with the story. Books 1-3 of the series bait us with intriguing events and characters while books 4-5 switch on us and tell stories largely outside the realm of books 1-3. Not that those stories shouldn't or can't be told... But they don't fit into this particular story because, in the end, they provide no real advancement of the things most readers care about. As an audience, our capacity to retain information and feel empathy has its limits. Martin went well beyond those limits, losing us in an immense world (and not in a good way) and continually introducing characters who only reminded us we weren't reading about the characters we cared about. It led most people I know to fatigue, then exhaustion, and finally anger because the books were no longer delivering on promises made in the first few thousand pages (and audience trust is a real thing that should never be ignored). If Martin wanted to tell a more substantive story about Dorne or Easteros, there is nothing preventing him from doing so in another series.