what was with soap-on-a-rope? i can remember my mom getting my dad an Old Spice soap like that and the joke was always "don't drop the soap" with a prison reference.
A person who is not agile because of age or disability would use the product to prevent having to bend over to pick up the bar of soap if it slipped out of their hand. I don't know the situation now, but in the old days, prison showers and also military showers had a row of shower heads on the wall and a group of men took showers together. I think you can figure the rest out for yourself.