It was a mix of opt in and controlled by the DM. Most of the rules were in the DMG, and probably for good reason. it's not something all players or DMs want to deal with. Over 15 years of 1e and 2e gaming, I had never been in a game with strongholds or followers. Well, that might be a fib. I think a 1e game started with our castle being burned down and the followers turned to an undead horde, although 30-odd years later, I could be wrong and we weren't the lords of the damsel castle.
3e at least released SBG fairly early in the supplement cycle, which wasn't totally horrible. Plus the feat did include cohorts, so there was some direct mechanical boost that could entice less RP-centric people to dip their toes in the waters. "Hey Ranger, want a cool pet that gets almost as many hit dice as you? Great, it comes with 15 adoring ranger-scouts and their families! Enjoy!"
4e....wasn't a bad game but it didn't taste like d&d to me. No clue about that.
5e is, as I said earlier, overly simplified for my tastes. We use the Kobold Press Tome of Heroes plus the d20 Magical Medieval Society:Western Europe to add in those elements to our game.