Anti-Microbial Peptides (AMPs) are produced by your skin cells (and sweat glands) to kill opportunistic bacteria and viruses on the skin surface. These peptides help to shape the skin microbiome as commensal microbes have evolved immunity.
Other AMPs are also produced by members of the skin microbiome to exclude invaders as they compete for nutrients on the skin surface.
This makes skin a pretty hostile environment for incoming pathogens. As an example, Coronavirus can stay viable on a non-porous surface for up to 3 days but residence time on skin seems to be around 3,5 hours.
If you know that you have high risk of exposure to pathogens, it makes sense to use soap to remove microbes from your skin (particularly your hands). But in your normal daily life, does it make sense to wash the AMPs on your face and body down the drain?