True, the career stand-still was bad enough with the TOS characters, though at least they continued to move up in rank, even if they kept the same jobs for twenty years. It's particularly bad in TUC both Spock and Scotty are captains yet they still keep their positions of science ofricer and chief engineer of the Enterprise.
But with TNG it just got silly. They all stay together for 15 years at basically the same rank and positions. The only one who moved on with their career was Worf, but even he gave it all up to become the Enterpirse's tactical officer again in Nemesis. Factor in the Federation fought a war where it suffered heavy losses, and the very idea that people weren't pulled off the Enterprise and promoted to fill in vacancies elsewhere in Starfleet really makes no sense.
DS9 at least ended with everyone moving on in their lives and only a handful of characters stayed on the station.
Voyager at least had a reason for why no one would transfer off the ship, being lost on the ass-end of the galaxy, but still one would think Harry Kim could have been promoted at some point Tuvok got promoted, Tom Paris got demoted and re-promoted, no reason Harry should have been an enisgn all this time.
And Enterprise, TATV claims that no one advanced in rank ten years, meaning Mayweather and Hoshi break Harry's record for longest ensign.