Do you remember the 2e henchmen rules? Because I do. There were no rules. It was a page of "at some point, a hireling will probably become a buddy. How? You figure it out. When? When somebody feels ready. Just make sure they are a few levels behind. Make 2 character sheets for them, give the basic one to player, keep one that also has motivations and backstory."
(I don't remember 1e rules, it's been 30yrs)
Hirelings had more rules but most of it was predicated on the PCs wanting to hire hundreds of people. Anyone who simply wanted a couple of teamsters to drive a wagon or a couple guards to protect livestock had little more than a price list. It was really some stealth stronghold rules.
I do think the DMG deserves one pages and maybe 3 charts on strongholds to provide a basic framework to spice up their campaigns.
It is a way for a dm to create a sink for gold, create new form of wealth (authority, respect, titles) for players to collect, create political ties, provide RP opportunities, motivation for evil characters to defend villagers, and a hostage to fortune. (No, not the villagers. The wealth the land represents)
Anything more than that needs a whole chapter and at that point get a dedicated supplement.