There is no need for additional bodyparts to achieve realistic bending. Too many bodyparts are a resource hog in Poser and make posing impractical. Left default David 3 with the standard Head->Neck->Chest->Abdomen->Hip grouping. Right a weightmapped version,using the exact same joint centers and grouping. Between weightmapping, bulgemapping, the morphbrush and JCMs, PP-2014 gives you full control over the mesh and its joints. It's just that demand for anatomical accuracy is incredible low in Poser, so hardly any figure creator bothers to transcendend the usual Ken & Barbie doll functionality. But Poser's technology is definitely advanced enough to give you any level of realism you need.