Why you say that? even in a white box you can put npc functionality on it.
The point is to have a standard top quality head for all artists, the work / hours of making a head compared to the rest of the body is abysmal.
If all artists on the marketplace use the same head system, it is a huge benefit for developers.
Who can buy only clothes without fighting 100 kinds of faces with different bones setup, morphs and styles.
and not only the marketplace, it is also a great saving in a company or if you want exclusive characters commissioned from a freelance artist