Epicurus did not tell people to do whatever they want. Rather his philosphy sounds rather like Bhuddism, with it’s emphasis on rampant desire as a source of unhappiness. It sounds as if he favored simple, low consumption living. The article points out that the use that was made of his name, epicurian, is the antithesis of his viewpoint.
All true. But when you eliminate any reason to reign in rampant desire, other than personal preference, most people (other than philosophers and their students) take that as license to do whatever they want. You see the symptoms of that in Rome (although Epicurianism may have been a symptom of existing sickness in Rome rather than a cause) and you see the same thing in America and Western Europe (largely, imho, as a result of secular humanism).
The parallel is actually quite remarkable. Philosophical secular humanists today all have systems that they think provide a non-religious reason to behave properly. That may work for them and their disciples; but in society at large, the message is "do whatever you want" because there is no reason not to. But perhaps they too (like Epicurians) are just a symptom (not a cause) of the degeneration of our culture caused by wealth, idle time, and endless nattering about feelings and other unimportant things by folks like Oprah.