I am inclined to agree with this. For a few of my important tasks like cramming for an exam, or banging out a paper the night before its due, I find the presence of the clock helpful/essential. but most of the other time it just something that takes up space. Its a bit like those overly technical conky scripts people run on their desktop coughing up information that is never used. The solution for me has been this:
http://fav.me/d34oqkg. The panel with the digitalclock plasmoid is set to let windows cover it, when I am not working on timecrucial stuff. I make windows go below it only when its important. Furthermore its not in a corner because I do not want to accidentally make it pop up via fitt's law, but close enough to the corner so that I can throw my mouse down in the corner and then move left.