Because of the risk that doing so could grant people from previous steps with access to materials they should not see — materials from the current step.

Technically speaking, if no new documents have been added at the new step, this may be done. However, if this is not the scenario — for example, if the Dean’s Office has already uploaded the Dean’s Statement (which the department should not see) — then there is no way for the Dean’s Office to hide that document from the department administrator and committee members who have access to the case at the previous step.

See Also

If I Send a Case Forward, Will I Lose Access to Its Dossier Contents?