If nobody is responsible for a specific job, that specific job will not get done. There is substantial truth in the saying : EVERYBODY'S JOB IS NOBODY'S JOB.
Job description of the departments and players involved in getting a job done must be defined and understood by all parties concerned. The keywords are : GETTING ONE'S JOB DONE AND NOT ANY OTHER JOB.
The point of this post is : In order for one to play one's role well, one must understand one's scope of job and responsibility ( as per the job description ).