I heard its a must method for cakes. But is it also a must for cookies? Cakes i understand since it needs to be light and fluffy. But cookies? Like sugar cookies or tuiles?
There are many cookies which are made via the creaming method, as it helps these cookies achieve the proper texture and leavening.
It is far from the exclusive method for cookies; there are many cookies which are made by alternate methods.
Many cookies, for example, are made with melted butter which does not have the ability to trap air the way solid butter or shortening does.
There are other cookies, such as French macarons, which have their structure and leavening from egg whites.