I use them always. Even in 5E, I still use the ancient BECMI advancement rules.
Most players are happy to have a retainer or two. Often a 'buddy' to help them in combat. But some clever players use them to guard things, fetch things and do other tasks. And often fill in holes.....like a fighter having a diviner retainer to "do magic stuff". While character's do just hire some, at least half are met on adventures and join the group.
Henchmen are often hired for a task.. As the players will often pick a spot as a "base", they will fill it up with henchmen.
And by Name Level (9th) most players are looking to do more then just "adventure like 1st level". And this is where Dominions come in. This adds a whole new level of play.
And then...at the peak of Master Level play.....is the Quest for Immortality. Yet another level of play.
I have had many players follow this long path over years...making their personal mark in the game world and loving it. Though only a few ever made it to immortality.
It is a LOT of record keeping and keeping track of things....but then that is what any player in my game must do from first level.