A student argued that no distinction should be made between commensalism and parasitism. Even in commensalism, the

Question:

A student argued that no distinction should be made between commensalism and parasitism. Even in commensalism, the micro-organisms are gaining some benefit (such as nutrients) from the host, and this represents a loss to the host. In this sense, the host is being damaged. Does the student have a valid argument?
Why or why not?