From the looks of it, no one knows the full reason for the job. The old man says no living human knows the reason and "we have inherited this duty ceaselessly" which seems to suggest it's been a tradition for many, many, MANY years.
I'm with the characters speculating that the gloves serve as a seal for whatever is at the center. My own take: the hands are trying to protect that seal and consider knowing anything about what's sealed to be too dangerous, including the location. Sole exception seems to be the designated inheritor, since they'd need to know where to place the gloves and there is a singular deployment chart.
All of the rules seem to be made by humans to try to maximize survival against the hands' inhuman logic: Trying to intentionally place the gloves shows you know they're important, so that gets you killed. Moving the gloves once dropped has potential to disrupt the seal and means you might know it's important, so that gets you killed. Whoever is holding the gloves when the hand notices them moved will be killed, so that rule is just to increase the glove dropper's own survival. It might be that the hands can only sense/see the people who are actively holding or have handled the gloves recently.
Ultimately, all the rules tie neatly together with the final rule: don't attempt to learn the purpose of the job. The hands do NOT want anyone to know, your best bet at survival is to play dumb. And it seems just seeing the hands can invoke some deep, internal understanding in people. Just seeing it from the outside like us manga readers wouldn't have that effect, we'd have to be experiencing it directly like the characters to get that sense.
I feel like that old man might reappear later in some minor capacity. That big liver spot on his head just feels too distinct to me. Maybe some big scene with a bunch of characters associated with Q?