Palpatine was revealed to have returned from the dead in Star Wars: The Rise of Skywalker, recontextualizing the previous films and proving that Luke Skywalker was the greatest of the Jedi. Star Wars: The Force Awakens and Star Wars: The Last Jedi established Supreme Leader Snoke as the leader of the First Order until Kylo Ren killed and usurped him. When Palpatine returned, however, the truth behind his machinations was revealed. Palpatine cheated death and controlled the First Order from the shadows, but Luke Skywalker was the only Jedi he ever feared.
Snoke's origins were shrouded in mystery until The Rise of Skywalker and canon non-movie material revealed his true nature. Snoke was a strand-cast who, despite having free will, was used as a proxy leader by Palpatine to bring the galaxy under Sith rule and turn Ben Solo to the dark side of the Force. Meanwhile, Palpatine remained hidden on Exegol, surviving in a weakened clone body unbeknownst to most of the galaxy.
Snoke, on behalf of Palpatine, was shown to be quite afraid of Luke Skywalker. Snoke’s primary objective in The Force Awakens was to find the map to Luke Skywalker and prevent him from aiding the Resistance. When Snoke finally discovered Luke’s location in The Last Jedi, he planned to obliterate Luke on his island from orbit rather than risk facing him alone. Snoke’s fear reflected Palpatine’s, and they were right to avoid Luke, as he was the greatest threat to Palpatine’s rule and perhaps the only Jedi who the dreaded Darth Sidious ever feared.
While Luke and Palpatine never fought in canon, the older Sith surely recognized the astounding Force power in Skywalker. With significantly less training than Anakin, Luke managed to best his father aboard the Second Death Star, and he’d only grow stronger as he continued to train. Luke’s power was not, however, his greatest asset, nor was it what allowed him to defeat Palpatine. Luke beat The Emperor with his sentiment. Luke’s genuine altruism and faith in his father allowed him to completely resist the dark side and turn Darth Vader against Palpatine, leading to The Emperor’s first death.
No other Jedi would have used the approach that Luke used. The prequel-era Jedi and even Rey, the first of a new kind of Jedi, relied on the strength rather than their sentiment, which played perfectly into Palpatine’s plans. Though part of a different continuity, Luke did engage Palpatine in several lightsaber duels in the Legends-era Dark Empire comics as well, besting the Sith Lord in one of their confrontations (albeit with Leia Organa’s help).
If Luke hadn’t entered a self-imposed exile during the sequel trilogy (behavior that many viewers found dubiously in-character), he would have been the only person who could kill or capture both Kylo Ren and Snoke and would have endeavored to bring his nephew back from the dark side as he did to his father. Perhaps Luke could have even discovered Palpatine’s survival, putting the Sith Lord’s long-term plans in jeopardy. With Luke, perhaps the greatest of the Jedi, gone and Kylo Ren leading the First Order in Star Wars: The Rise of Skywalker, Palpatine was finally safe to reveal himself to the galaxy.
