Why is the empennage of some aircraft not placed on the centerline?
The vertical stabilizer is on the centerline.

The line you see is not the centerline, it's the overlap of the aluminum sheets that form the circular fuselage.

(Source)

(Source) Non-aviation example of what I mean by overlap and centerline.



On the other hand, propeller aircraft may employ different methods to counter the left turning tendencies.




  Tail
  
  The tail group consists of a vertical stabilizer, a horizontal stabilizer, two
  elevators, and a rudder. The vertical stabilizer is mounted on the aft
  fuselage, and the horizontal stabilizer is mounted on the top of the vertical
  stabilizer. The rudder and elevators are mounted on the vertical and
  horizontal stabilizers, respectively.
  
  The vertical stabilizer is fully cantilevered and sweptback. A scoop for
  cooling the air-conditioning systems is located on the lower leading edge
  section and is heated when the Airfoil Anti-ice is operating.
  
  – MD-80 Flight Manual


Back to the MD-80 in the photo, from its manual there is no mention of an offset. I searched for multiple terms such as offset, angled, and off center.

Finally, from an official CAD drawing from Boeing's website: