Gia's response at first appears kneejerk and prejudiced by her former profession, but I think what she might be trying to say is that pubic hair has lost the function it once had when we were a much more intimately social animal. It served as a bottleneck/barrier to crawling parasites and at one time we could count on another member of our group to pick these out and eat them. We can no longer count on this, and so it has degraded into a place of mushy dandruff and festering filth (with crawlies) unless regularly plucked/shaved/waxed, etc.