I consider this fairly irrefutable. Water, Time, heat, and scrubbing with an abrasive are sufficient to get your body clean eventually it’s just a question of effort and technique. Having said that, you claim you are still using soap on hands and feet and hair. So presumably you too have found utility in soap for those areas. It’s not completely a hold over from cold water.
Discussion
Right, BC soap is still needed for bacterial removal, and wiping your ass has bacteria, and personally, my feet at trapped in boots all day BC of thorns (one day i would be able to ranch barefoot), and hair is just a dime a month.
So a reduction of 30x is huge.