> Water washes off odor but not the bacteria that make that odor.

That is simply inaccurate.

"Bacteria of potential faecal origin (mostly Enterococcus and Enterobacter spp.) were found after no handwashing in 44% of samples. Handwashing with water alone reduced the presence of bacteria to 23% (p < 0.001)."

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3037063/

Whether body soap is necessary for you in particular to not smell bad I cannot comment, but it certainly isn't universally true.