As Bryan mentioned, fraternization is one issue.

More important is that while the enlisted men are issued rations (food) from the Army commissary, officers are required -- even today -- to provide their own meals, both in garrison or camp as well as in the field. They may purchase items from the commissary under certain conditions, but must pay fair market price for them. If the officers were dipping into the enlisted men's rations, that results in a diminished ration for the enlisted folks and that just ain't right.

Tom Ezell