Just a slight precision ..

As I remember the discussion, either I did not ask "why" or if I did it was a rhetorical "why". I believe I know why the various organizational methods / practices for dealing with (or managing) human processes are in silos ... I just think that they don't need to be fully silo'd.

I'm prepared to admit that there are some arcane specialties that demand specific expertise at key points, but I also think the emerging conditions for working networked organizations beg the issue of all of HR, much of IT and line management addressing the issues in common to seek synergies and leverage that make sense and are practical.