I'm not saying that TOS was totally sexist. It was done in the 60s for goodness sake. And women actually being on board a naval vessel was a huge step-forward compared to the military at the time and even nowadays. They had women doctors, lawyers, senior scientists, a woman in charge of the dilithium crystals. OK a lot of these women were just love interests for Kirk or someone else but the realities of a TV series in that time is that you had to double-up some of the roles. If you look at 'Court Martial' and you see the group of Captains that were snubbing Kirk. None of those were ladies. You never saw a lady captain. The only 'command' female you ever saw was in 'The Cage'. The only time you every saw a woman take the command of any Federation vessel was in 'The Cage'. It never happened again. And sure you could say the Captain of say the Endeavour or the Kongo or the Republic was a woman or a Vulcan or an Andorian but we never saw any evidence of that. And there's the talk in a couple of episodes that it takes a special 'man' to be a Starship captain, not a special person. And to the people who point out why would Number One agree to serve on a ship where she could never be Captain. I think its like the current Navy. Eventually you hope things might change. It is only in the last few decades that women could serve at sea on Navy Ships in my country. In the 60s if a woman was in the Navy (or Public Service) they had to resign when they got married. Perhaps Number One was in the Service killing time until she found a husband.