The general plot to Avengers: Endgame leaked before the movie was released and it was both dismissed as being too ridiculous to be true, while others felt that if the leaks were true it would be a terrible movie. The leaks did turn out to be pretty accurate overall. yet now Endgame is considered one of the best films in the MCU. I think most films would/could sound pretty boring and/or strange when all you have are simple scene summaries without any of the dialogue, performances, music, cinematography, etc. to make them engaging. Plus, the people who leaks movie plots don’t usually have the full scripts at hand, but have found ways to “peak” into the production, and that’s definitely bound to strip away a lot of nuances and important details.

Also, its completely possible that fake leaks can end up being accurate by accident. There’s only so many tings you can logically do with an established franchise, and I think people have guessed the plots of SW movies pretty well in the past.