Honestly, this is a pretty good example of a long-term trend we've seen for years in modern screenwriting.
We've somehow ended up with a cadre of writers who are just bad at their jobs.
They do not think through the logic of their stories, they don't know anything about the world, they don't understand people or human motivations in any meaningful sense, they're obsessed with current-year politics and don't really have a brain in their heads outside of buzzwords and tropes, and they are completely and utterly lacking in all self-awareness.
You might think I'm being hyperbolic, but... I'm really not.
There's a ton of stuff in TLJ like this, where the writers/Rian Johnson clearly had a particular idea as to what story they were telling, and yet scene after scene undercuts the coherence of the story and messages they were pushing.
But consider that virtually every bad movie or show in the last couple of decades fits this same pattern.
Scenes make no sense. Actions do not follow any semblance of cause & effect. Character's actions do not have any real effect on the plot. People don't behave in ways that seem sane or human. Character motivations and capabilities get ignored or swapped out of storytelling convenience. Dialogue is all cringey political diatribes and modern slang that doesn't survive a year before becoming embarrassingly dated.
Their goals aren't telling a real story that has any sense of verisimilitude or immersive reality to it. They're just using $200 million dollar toys (mostly IP created by better writers long before they were even born) to push idiotic messages and use characters as self-inserts with the primary purpose of becoming mouthpieces for their completely monolithic and largely extremist ideology.
Point being: These aren't "mistakes".
Holdo was one of several girlboss characters in TLJ. Girlbosses can never be wrong. They never make mistakes. They display their importance by lording their power over others in ways that would never actually fly in a male context.
I mean really... How many times have you seen a male general, police chief, boss/manager undercut the protagonist in a story prior to now? How many examples can you think of those guys being "proven right" by the events of the story?
Almost never. Instead, they're presented not only as wrong (and sometimes outright incompetent or corrupt), but also as the assholes they are. The (also male) protagonist gets one over on their own boss, and we root for that outcome because we believe in the hero of the story and want them to overcome their dumbest obstacles.
Now imagine a world in which the angry police captain is right, or where the blustery antagonist military general's command to do something we know won't work against the recommendation of the story's hero who's actually fighting on the front lines turns out to be tactically genius, or one where the protagonist is constantly undercut and treated like an idiot throughout the story and never gets a real moment of triumph.
Would you still be rooting for them?
You know you would not.
And yet that's exactly how modern writers treat both female protagonists, deuteragonists, and antagonists -- especially when their counterpart is male.
Poe *had* to be mistreated, silenced, kept out of the loop, and then shown to be yet another mansplaining dumbass who should have just bowed down to his superior (Holdo) and done exactly what she said. Otherwise, Holdo -- a woman in a significant position of power -- might be shown to be incorrect about something, which would undercut the writers' ideological need to mock white men (which includes Oscar Isaacs in this case), and "elevate" women.
That's how the girlboss thing works.
It's not an accident.
One of the biggest mistakes this movie made was how it handled Poe.
Having Holdo’s idiotic decision to keep vital strategic information from her most popular and well known soldier… is actually fine.
If it were played as a mistake that is.
But because it’s played as Holdo making the right decision (despite all the clear evidence to the contrary and the fact that her plan would’ve gone off without a hitch if Poe had been backing her play instead of being pushed into mutiny.) it turns her in to an incompetent leader while also praising her for her incompetence by making it a ‘mother knows best’ type of situation.
And everyone is sick of people whose incompetence is covered over by immutable circumstance.