Narratively rank is very important especially when you are trying to demonstrate a paramilitary organization in the confines of a television series. I think there are probably often arguments about this. Why is Ezri written as a counselor and an Ensign instead of a science officer of a higher rank?

I do think there is real world relevance sometimes. We see Worf and Geordi get promotions and become a larger part of the series with more screen time and character development. This works narratively to distinguish the change. An “on screen” promotion indicates some sort of character growth. We see this happen with Sisko likely because the only reason to distinguish him at first was because he was written to have a fairly minor (in universe) role which was greatly expanded.

In recent years I think rank has been downplayed as there are so many inconsistencies and patterns and anti-patterns throughout the series. It’s important that you’re able to tell a story where if someone is supposed to be in charge they have the appropriate rank for this. This is one of the reasons Discovery effectively promoted Tilly rapidly (all the way to being the XO for a little bit) because she was a pivotal part of the cast and needed screen time. In fact Discovery doesn’t “ignore” rank it rather ignores rank conventions by having a mutineer on the bridge as a ‘specialist’ and a command staff that almost just takes turns at the wheel.

In Lower Decks we can assume narratively no one is going to get promoted permanently or demoted permanently because the show depends on that dynamic. If we look to Strange New Worlds we see rank downplayed to a large degree because everyone’s rank is so close together. This is important to get Spock of a low enough rank so that he can be promoted to commander later. (Frustratingly there are still inconsistencies here. There seems to be confusion between Lt. and Lt. Jg. and Nurse Chapel’s rank, which may be provisional because she may be a civilian contractor who has a temporary commission and then later joins with a regular commission of a lower rank - or her rank is just not important - is also out of continuity.) But importantly for SNW - narratively it makes sense to have these people of these ranks in these positions so it just works.

In a more realistic depiction people would be moving through ships much more quickly. There would be fewer officers and they would move through the ranks regularly and not stay in one position for 7 years. Likewise mostly Enlisted people would be spending a few years at most and moving onto other careers in civilian life as most people don’t want to be in the military forever and if they do they become officers. Miles O’Brien (despite the insignia being weird) is probably most accurately depicted. He served on many posts, he left posts for some period of time and then returned to them in new capacities, he moved between posts. He joined in 2345 and by 2375 he was probably ready for retirement or in the case of a utopian future, moving back to Earth to teach at Starfleet until he is absolutely ancient because he’s got nothing better to do and he loves his job.

This is one of the reasons Discovery effectively promoted Tilly rapidly (all the way to being the XO for a little bit) because she was a pivotal part of the cast and needed screen time.

It's a testament to Mary Wiseman's acting that the writers sought to give Tilly more screen time. But the way they did it made my eyes roll through the roof. I did not for a second consider it believable that an Ensign, only a couple (?) of years out of the Academy, would be skyrocketed through the hierarchy to become the Chief Operating Officer of the ship.

Tilly's promotion was even more unbelievable than when Jed Bartlet made CJ Cregg his Chief of Staff, elevating her above her Toby Ziegler (whom she reported to) and Josh Lyman. I know why the writers did it - because Allison Janney was the best actor in a world-class ensemble, and they wanted to give her more to do. But it didn't ring true to me (even though there is an argument to be made that all the West Wing characters are so hyper-competent that reporting lines are mere formalities).

Sure, you could argue Starfleet has a history of promoting promising youngsters unbelievably fast - like when they gave that cocky repeat offender fresh out of school command of the most modern ship in the fleet simply as a reward for saving the world. But even so.

This actually goes to a related point about DIS and how the writers treated the rank of its main character. Discovery was notable in that it was the first show where the lead actor was also not the most senior member of the crew. As David Gerrold pointed out in The World of Star Trek (IIRC), there's a reason why the captain is the star of the show. Because in a crisis all decisions come back to that role. And the ability to make decisions is what makes for good characterisation (Hamlet notwithstanding). But if the command decisions, the decisions around which the plots and the drama pivot, are ultimately made by someone other than Michael Burnham, more senior than her and who can overrule her, what do you do then? Well, you make the Captain a baddie (like in season 1) or you find other ways of making the main character go against orders (which Burnham did repeatedly). Unfortunately that led to a backlash because the character, Mary Sue-like, was always proven to be correct whenever she went rogue.

I actually liked the fact that the lead character in DIS wasn't the CO. But - like Tilly's promotion - I just wish the writers had found a better way of exploring that dynamic. Having Burnham assume the traditional captain's seat in season 4 was - in some ways - an admission of defeat, but an understandable one.

Lower Decks of course pulls it off, but as a comedy the stakes are generally lower, and the fact that the main characters often don't know what's going on, or aren't in a position to decide how to shape events, is part of the gag.