The Vulcan captain may not have been as famous as Spock. Then again, not like TOS mentions that many famous anyones in Star Fleet. Might have just had a lot more seniority than Spock - with a 200-plus year lifespan, expect that Vulcans can put in a LOT of career time.
Regarding the ships at the Star Base, there may have been something "big" happening or impending in that particular sector (and unmentioned in the CM episode). Wargames? Fears about a hostile incursion? That would explain three starships being in the same patch.
Also, not to get into political correctness, but who says the Vulcan captain had to be a "he"? Fairly
sure that the gender of the 'Intrepid' CO is not mentioned or implied anyplace in TOS.