In GEN, a reporter says to Kirk, "This is the first starship Enterprise in 30 years without James T. Kirk in command. How do you feel about that?" The reporter didn't do their homework because they forgot about Decker and Spock.
I'd rather suspect the fans are forgetting, or ignorant of, half a dozen other people who commanded the Enterprise at one point or another (there's plenty of room for Captains Nowan and Nnevahurd between the first two movies, say).
But the reporter got it right: all the previous versions of the Enterprise in the past 30 years did have JTK in command. And, of course, the E-B ultimately did, too... For all of twenty seconds or so, before he graciously relegated command back to Harriman.
But Decker never got a chance to command the Enterprise on active duty and I'm guessing Spock was never too far from Kirk when the Enterprise was a training vessel. So, even though it's sloppy, I can see why the reporter would make that mistake.
Not a mistake at all, but an angle. Nothing about what she says is incorrect in the slightest. Nobody cares about Decker or Spock or Nnevahurd. The story is about Kirk, who commanded at least two previous Enterprises and, the circumstances of the refit considered, more like three.
After just re-joining Starfleet, I don't think they'd give Spock a command of his own right away... so I'd say Kirk stayed in command of the Enterprise for a little while after TMP.
Or got kicked out of the service when Nogura grew a spine, and crawled back to beg for a desk job, which ultimately meant position as Academy Commandant.
Starfleet can't really be short of capable commanders of starships. There just happened to be a temporary and local shortage at the exact hour of TMP, which Kirk ruthlessly exploited. After Kirk's unscheduled joyride thataway, the next man, woman or BEM would be ready to take over.
Timo Saloniemi