All employers are different, one can get fired unexpectedly and for no legal reason. If there is no clear and written agreement between an employer and an employee, than employer can state avoid stating anything as the reason for dismissal. Some companies prefer doing so, as they can create any reason afterwards in case an employee demands an appeal.
An employee can also benefit from it, as they can call any contract termination a dismissal. And in this case they are subject to benefits as unemployed.