A difference between fiction and nonfiction and why Feast of the Goat fails

In a pattern that's become all to familiar, and frustrating, for me, I'm abandoning Mario Vargas Llosa's The Feast of the Goat about halfway through - there's nothing actually wrong with the book and I started it with great hope as I found the first chapters a very promising start, several key characters introduced, the dictator Trujillo, people in his entourage plotting against him, and woman returning to the Dominican Republic after many years to learn the truth about her father and his service to the tyrant. But honestly V-L establishes these themes and characters and then in my view does not develop much of anything; we can easily see the architecture of his plot, and we know the key events pretty soon - Trujillo will be assassinated by a gang of 7 men whom he has alienated by his tyranny - and it seems to me that V-L just hits the same notes repeatedly. I'm not curious about what's going to happen next and I don't know much more by chapter 16 than I did at chapter 3 - there's just a long concatenation of incidents and details. A great novel, or any novel, needs and architecture and a design - which is not the same thing as a scheme (alternating pov by chapter among three strands of plot, for example, as V-L does here). I remember being similarly frustrated by his long novel The War at the End of the World, and maybe it's me - but it comes down to an essential difference between fiction and nonfiction, between acts of the imagination and pursuit of facts, between art and skill or craft: even the greatest nonfiction (take the LBJ bios by Caro) must hew to the facts of the case before it - whereas fiction, in pursuit of different (maybe higher) truth is free to soar. It's as if in this novel V-L is totally earthbound, plodding onward with his theme, dutifully, step by step, and despite its various strengths, which I have noted in previous posts, a few powerful chapters in isolation and some intriguing allegorical hints (the dictator like a jealous God - what I had picked up as a subtlety in the chapter in which Trujillo turns against the Egghead becomes explicit in the next chapter when Trujillo meets with his acolyte, the puppet president), the novel has a lot of detail but doesn't move anywhere, doesn't hold us, or didn't hold me, in suspense and wonder.