The point is that it is not the words themselves that hurt you. It is the people who act on those words. Words are serious, not because they have any direct effect in their own right, but because words, and the ideas they express, are what we use to weigh up our own decisions, their likely effects, and our responsibilities. Words have consequences only if we choose to give them consequences. It is not the words themselves that cause things to happen, but our estimation of the value, and truth, of those words.
Freedom of speech is often misunderstood to be a gift to crackpots, racists, or demagogues.
But the truth is the opposite. The people who are really empowered by free speech are not the speakers but the audience. Free speech puts a premium on the decision-making ability of each of us to weigh up all the arguments and draw our own conclusions. The idea that speech can kill implies that the responsibility for acts of killing lies not just with the individual who carries out the act, but also with the words themselves. Rather than particular social circumstances influencing the interpretation and value put on words, the words themselves are portrayed as bearing some responsibility for acts.