Presumably this rule was written to prevent a college athlete, whether from a Division I sports juggernaut or a Division III college like Macalester, from making piles of money after revealing he is an intercollegiate athlete. The N.C.A.A. wants to prevent some Heisman Trophy-winning quarterback or some one-and-done power forward at the University of Kentucky from writing a book or modeling a sweater in order to profit from his collegiate athletic celebrity.

Of course, the reasonable response to this concern is: What’s wrong with a person profiting from his own accomplishments and celebrity? Isn’t that more or less the way it’s supposed to work? But the N.C.A.A., not content with the billions in TV and merchandising revenue it already takes in, is determined to leave no spare change under the couch cushions.

Lest you think I exaggerate, look up the case of the two athletes at the University of Iowa who started a T-shirt screening business and were threatened with ineligibility by the N.C.A.A. because their website mentioned that they met because they were both — brace yourself — swimmers. Or the more recent case of a cross-country runner at Texas A&M who was threatened with ineligibility for posting a YouTube video about a water bottle company he started.

The most repugnant aspect of this N.C.A.A. rule is that it runs directly counter to the optimal American college education. We want students to have multiple interests, multiple facets to their personal and academic lives, and to explore openly how those various identities play out. We want a student athlete to think — and talk — about what it means to be an athlete and an author, or an athlete and an entrepreneur, or an athlete and an artist. But a student who designs and sells greeting cards and mentions on her Facebook page that she is a softball player risks losing her athletic eligibility. That is shameful. Bylaw 12.5.1.3 has got to go.

Given all of the stereotypes about student athletes as prizing sports over academics, one would think that the N.C.A.A. would be enthusiastic about opportunities to shatter those. But given the choice between doing so and inadvertently allowing an athlete to profit from even the most tangential connection to his or her own athletic efforts, the N.C.A.A. has decided to force students to disguise who they are.

For those few students who star in Division I, it is an invitation to enter into a sad but unsurprising underground economy. For Division III athletes, the hypocrisy is a dispiriting act of silencing. For anyone who cares about fairness, it is a disgrace.