It surprises me why there aren't joint defense funding efforts in place to put these industry pests to bed... One barrier to collective action is that the courts only give you a limited number of attempts to kill a patent (usually one, but sometimes sort of two). So if you join up with a group, that group's attempt is attributable to you, and your one shot is used up. This effect, called an estoppel, is one reason you don't see more of this.