What is wrong with the common notion that says, "the ends justifies the means"?

Why is capitalist society, including particularly the U.S., and nakedly so with Trump, thoroughly saturated with the view, and the reality, that means - no matter how criminal, brutal, and inhumane - are justified if they serve the interests of the ruling institutions and forces?

Why does the new communism brought forward by Bob Avakian thoroughly repudiate this, insisting that "the means should flow from the ends and be consistent with the ends." Ends, which are in Avakian’s view, eliminating racism, domination of men over women, unequal relations between nations, discrimination against LGBTQ people, and the underlying oppressive economic foundations of society.