It is more like burying garbage to composte it. Well, I don't find this too significant. Lots of this area has not been excavated. Buildings could well have been built over the centuries on such sites. In every city there's a place where strangers and criminals and slaves are interred.
Nobody wants to have dead bodies lying around.
Such places could have been different at different times. Think of the times of wars, epidemics, famines and such. Thousands of people would have been dying and buried in mass graves. But there's no doubt that such mass graves are there somewhere. Now, this is important.