Many people think that semi automatic rifles are used frequently in homicides. The popular phrase among gun control advocates has become "why does anyone need an AR-15?".
While many gun control advocates may think that rifles are used in thousands of homicides a year (specifically in mass shootings), the reality is that homicides by rifle (any rifle) are extremely rare. According to the FBI, only 322 homicides were committed with rifles. Compare that to 1,589 with knives, 518 with blunt objects, and 678 with hands/feet. (NOTE: Some of these homicides are considered justifiable)
Thus, it simply makes no sense to institute a ban on "assault weapons", which are more accurately known as semi automatic rifles. Gun control` advocates who want to ban rifles simply aren't thinking rationally and most likely, their judgement is clouded by their irrational fear (or disgust) of rifles.