Here is another example of a simple error of omission that could have been caught if the student had read the essay aloud or given it to a friend to read. The word "of" should be between "calculation" and "the." That one small error makes the entire sentence awkward and confusing. If the instructor has to reread the sentence to try to understand its meaning, the flow of the essay is interrupted. If this happens often enough in the essay, it gives an overall bad impression on what otherwise might be a very good paper in terms of research.
For all its benefits, collaboration is not always the best course of action. The process is fraught with dangers and inherent limitations. It is notoriously time-consuming and is not suitable for problems that require quick and decisive action, for example. Power inequalities among the parties often thwart the process. The norms of consensus and joint decision-making sometimes require that the common good take precedence over the interests of a few. It can break down in groups that are too large. And the process is meaningless when participants lack the power to implement final decisions.