yeah, a hard freeze in season wouldn't do that. What happens is if you have a warm spell mid-winter, after the trees have "gone to sleep", the sap will start to rise early. Then when there's a hard freeze it will kill the more tender, less hardy newer growth, or at least damage it sufficiently so that it won't put out leaf buds. Eventually the twigs will die and they'll snap off without too much trouble.

We had a warm spell followed by a very sudden, VERY hard freeze one year when I was living in Portland, where they typically get fairly mild winters. This was VERY cold, way below freezing. The trees were full of sap and when the temp dropped to below zero in just a few hours, all that moisture in the tree limbs suddenly froze and expanded. Trees were literally exploding. It sounded like a constant barrage of gunfire. It was really something.