I largely agree with you on the question of grade disclosure. Since business school is intended to foster teamwork, it is difficult to maintain this same level of teamwork and networking while you are making great effort to beat everyone else in your class. Nondisclosure allows students to concentrate more learning that worrying over narrow grade-based zero-sum rivalries with their classmates. However, employers often devise ways to get around grade nondisclosure regimes with varying levels of accuracy with regard to predicting the actual academic performance of students. In addition, there is a risk that students might not exert a full effort in class if they feel that employers will have limited access to their grades.
One could view a nondisclosure policy as a sign of the high opinion students at a given school hold of their fellow students. Indeed, it could be viewed as an assertion that "we collectively are so strong that I do not mind being counted as being one among this impressive set of students." Not surprisingly, one tends to see these policies in schools in the ultra elite and elite clusters. One the other hand, those schools/student bodies that emphasize grade disclosure tend to be from lower clusters. This could be viewed as a tacit assertion by the school that there are some weak students in the student body who the school should have provided with additional help, should have expelled, or should have rejected in the first place.
Of course, this issue is complicated so one could have other interpretations of encouraging disclosure such as a desire to maximize the provision of information to the market.
Hjort