We do need soap (and detergents) to clean our clothes but I think the scam is moving this genuine use of soap over to 'cleaning' the body, which has mostly only happened over the past century (and just the last ~50 years for use of detergents on the skin & hair, which can be much more harmful than soap). One of the earliest big advertising/consumer campaigns was to get ppl to buy soap in the first half of the 20th Century, from which the name 'soap opera' derives (these radio entertainments were sponsored by the soap companies as an advertising vehicle).