When the name was given, it still had that ability. For example, fmage rdruid spriest called god comp right now (came from pre 5.2), since they couldn't die. Now 2 patches later, some balance changes happend, sp got weaker, but it dosen't mean the name will change with it.
God comp is a god comp, people just used to call this setup that and eventually associate with it. Even if it dosen't feels so godlike anymore