Things are looking up for people who sign their full names when posting online comments and, for their troubles, get blind-sided by people who use pseudonyms to hide their true identities so they can post nasty comments about other individuals without owning up to it. That rabid breed is known as anon-persons, defined as creatures who can't accept responsibility for their own words or deeds and so play the "Who, me?" card by provoking and turning tail in the same bad breath.
Sometimes, the nasty comments border on libel or character defamation, absent any evidence, or, for that matter, any consequences for the attacker when the allegation is patently false, as usually it is.
Just as shouting "Fire!" in a crowded public space is not freedom of speech protected by the First Amendment, trying to damage someone's reputation and personal good will is an abuse of freedom of speech and what must be protected is the right of the aggrieved party to take action.