You commit fraud if you make any intentional deception in order to benefit yourself, or to harm others. If you intentionally make public commitments that turn out to be false, and you thereby cause some harm to another person, you have committed a fraud.
The FTC is empowered to enforce criminal and civil penalties for fraud on behalf of consumers. From the FTC website: "When the FTC was created in 1914, its purpose was to prevent unfair methods of competition in commerce as part of the battle to bust the trusts. Over the years, Congress passed additional laws giving the agency greater authority to police anticompetitive practices. In 1938, Congress passed a broad prohibition against unfair and deceptive acts or practices.”
From the FTC's Facebook settlement statement, it's perfectly clear that the FTC believes that Facebook is guilty of committing widespread and repeated deceptions in violation of the law.
The settlement itself is tantamount to saying that Facebook has had its last warning, and is on very thin ice with the FTC.
Feel free to complain about whether such a "penalty" is effective. We won't really know until the next time Facebook breaks the law.