Considering many of the "professionals" often make the same mistakes listed above in official and unofficial tourneys, I'd say everyone makes mistakes.
The article above summarizes all the mistakes both "professionals" and "amateurs" often tend to make, either because of forgetfulness, tiredness, or to some extent, their failure to understand the concepts.
Not only will this article assist amateurs to understand the concepts, professionals can always read the article and review what mistakes they had made in previous tournaments, instead of flaming and whining about a simple