Yeah, I don't understand why any DM would need or want to do this. I mean, sure, its possible it might be hard to get the exact same players at the table next week, but there's always ways to deal with that. AFAIK Gygax et al just did some switcheroo with who was or was not a PC vs a henchman. So the rogue's player is not around, but the guy that normally plays the fighter is. Guess who happened to be hiring himself out? The rogue gets treated as an NPC for the session, and one of the men-at-arms turns out to be the dwarf. Or someone starts one of the hirelings as a new level 1 PC, or just plays a henchman, etc.
Yeah, there could be an issue where later in the week some other PCs would like to go hit the same dungeon, but its in a 'quantum state' because actions haven't been dealt with that happened yesterday. Well, again, how hard is it REALLY to handle that? Most of the time not a biggy. The other party goes somewhere else, runs into trouble, explores a different level, etc.