There are many items in our culture that are great at holding back dammed up primal feelings and energies. Marriage. Laws against murder. Cultural norms about how to be civilized in public situations. All these are necessary at a level for a functioning society. But when our inhibited culture over-reaches into almost every aspect of our daily thinking patterns, we tend to get many neuroses arising. Dammed up sexual energy or rage are two examples. During Breathwork session, some of these feelings may be touched upon. They are welcomed.
We don't have to be 'nice' all the time. Some people are very shocked that such feelings are even residing inside themselves. Just acknowledging that they are there and speaking it clearly within a group setting can be enough to help relieve any deep internal tensions. As Freud
noted early on in the 20th century, it takes alot of energy to be civilized.
In the world of Breathwork all feelings are welcomed, all energies are welcomed and worked through either through the breath itself or some integration work at the end of a session.