The entire Holdo subplot was truly bizarre. Almost every aspect of it is difficult to make any sense of. Holdo withholds information mysteriously, and dialogue and directorial cues suggest to the audience that Holdo is hiding something, or that she might be a spy or perhaps be suspicious of a spy onboard. But then it turns out she was just hiding information for no reason. My take on this weirdness is that Rian Johnson thought this would be another “surprise reveal” or something, playing with audience expectations by subverting conventional story-telling tropes. But it just doesn’t land. It comes off less as some interesting reveal and more like an incoherent script. Nobody really knows what Holdo was thinking or why she decided to withhold information from Poe.
Unfortunately, since this whole issue is also wrapped in typical culture war nonsense, it’s often difficult to discuss online without emotions flaring up. I’ve seen some people argue that Holdo’s actions make sense, because she didn’t know if Poe could be trusted. Except Poe just destroyed Starkiller Base yesterday, so he’s probably the LEAST likely person onboard to be a spy. This fact gets lost on the audience, because The Last Jedi doesn’t really feel like it takes place one day after The Force Awakens. We go from triumphantly celebrating the destruction of Starkiller Base at the end of TFA, and presumably a devastating blow to the First Order in general, to suddenly being thrown into a situation at the beginning of TLJ where the First Order is rapidly conquering the entire Galaxy somehow and the Resistance is on the run.
TFA (along with out-of-Universe promotional material) suggested that the First Order was sort of analogous to “Nazis who had escaped to Argentina and started a little movement”. Thus, our impression is that they are nowhere near the same scale as the Galactic Empire, and they were relying entirely on Starkiller Base to gain any military advantage over the Republic. But then in TLJ, it seems the First Order actually is a much larger organization with military resources at least comparable to the Galactic Empire, and that destroying Starkiller Base was only a minor setback for them. TLJ also seems to confirm that the entire Republic was destroyed in that one attack from Starkiller Base in TFA. But none of this is explained to the audience, so TLJ just comes off as weird and disorienting, making it feel as if a lot of time has elapsed between movies.
I suspect that Rian Johnson just assumed the First Order was supposed to be dominant in TLJ, brushing off the destruction of Starkiller Base like it was nothing, because that’s what happened with the Galactic Empire in Empire Strikes Back, despite the destruction of the Death Star in A New Hope. Except, A New Hope established the Galactic Empire was already the dominant government controlling the Galaxy, whereas The Force Awakens at least suggests (although doesn’t really confirm explicitly) that the First Order is more like some rogue state that doesn’t have anywhere near the manpower of the Galactic Empire.