Why do dogs try to cover their poop?
I cannot find any definite articles on why there would be a reason for this behaviour other than the same ones that you have mentioned in your article. It could be because it wants to mark its territory or the dog wants to hide its scent. 

One point that I would also like to add is force of habit. As Charles Darwin (the father of evolutionary biology) had said in his book titled "The expression of emotion in man and animals"


  ‘Certain complex actions are of direct or indirect service under
  certain states of the mind, in order to relieve or gratify certain
  sensations, desires, etc.; and whenever the same state of mind is
  induced, however feebly, there is a tendency through the force of
  habit and association for the same movements to be performed, though
  they may not then be of the least use’ (reference 1 and reference 2).


It is more of a guess that we make when we see them hide their faeces but in the end, there may not be a reason at all but a habit that do not serve much purpose passed on through evolution. It is left upto our own liberty as to guess what the exact reason is.