@Tfmonkey They conquered ISIS and kept the name, similar of how the progressives conquered the United States and kept the name, or how the progressives replace a countries leadership by their puppets (effectively conquering them) and keep their name.
People don't like to think to much so if they see that the thing has the same name, they will fight for it as if it was the same thing all along, just like in Ukraine. Ukraine used to be very pro Russia, but look at them now... It's like parasitism