AOBs are found in soils pretty much everywhere. But they're extremely sensitive and can easily be washed away. In contrast, the particular microbes that have closely evolved alongside us to adapt to our skin microbiome often live several layers deep in our skin. When we take a hot shower or soap up we kill them on the surface but, luckily for our skin's health, they can be replenished. However, the AOBs don't have this deep relationship with us because they are not anaerobic. Instead it's likely that we've evolved to expect a constant influx of soil-based bacteria on our skin

Indeed if you look at any other hairless mammals, one of their favorite things is mud baths. Elephant, pigs, rhinos, etc. We're still learning the full extent of how our skin microbiome plays into our health, but the recent research on the gut-brain-skin axis shows it's likely deeply integrated into our evolutionary past