Imagine you're the screenwriter for a major studio tentpole blockbuster that's got thousands upon thousands of fans who are eagerly awaiting its release. They're swapping dozens of theories and potential plot points on Internet message boards, and you want to keep it that way, keep them in the dark so they'll be surprised when they finally see the movie.
Still, that's not always the case with hackers and other digital vultures looking to pilfer and disseminate shows, movies, and scripts that don't belong to them along improper channels before the proper release dates.
With today's methods of stealing, writers and directors need to get creative, and sometimes the solution is simply cutting yourself off from the rest of the world. Speaking to The Wall Street Journal, Last Jedi writer-director Rian Johnson gave up his method for keeping script-based spoilers off the internet:
"I typed Episode VIII out on a MacBook Air. For security it was “air-gapped”—never connected to the internet," he said. "I carried it around and used it for nothing except writing the script. I kept it in a safe at Pinewood Studios. I think my producer was constantly horrified I would leave it in a coffee shop."
Some security breaches are bigger than others, but if it had happened to Disney/Lucasfilm's Star Wars: The Last Jedi, the results could have been catastrophic. Not of biblical proportions, but part of the fun with any major franchise is going ignorantly into the theater with your fellow fans. Even after all the trailers, featurettes, and TV spots, you go in wanting to be surprised by something.
Johnson also said he listened to the "History of Rome" podcast (hosted by Mike Duncan) while writing the screenplay. The grand historical narrative of empire-building and larger-than-life leaders helped inspire the plot. "The stories have a lot of similarities. They’re about family dynamics and family politics. They’re about war and the mechanisms of war. You’ve got characters like Nero who are these insane, larger-than-life, operatic madmen driving their country to ruin. It’s very timely."