It’s possible, you know. It happens when you beat butter and sugar too long or too hard, and the sugar begins to dissolve in the mixture (which it can do because butter is about 17% water). Thus you can tell when you’ve over-creamed by rubbing the mixture between your fingers. A smooth-feeling cream means you’ve over-done it: the sugar crystals have dissolved and the air pockets have collapsed.
A similar thing can happen if your butter is too warm and/or you attempt the creaming method when the temperature in the kitchen is much over 70. Part (or all) of the butter will liquify around the sugar crystals, collapsing the air pockets and compromising the leavening. This is why you tend to get flat chocolate chip cookies when you mix your dough on a warm day and fluffy ones when you do it on a cool day, even though you’re using the same technique and the same ingredients. Temperature makes a big difference.