Nobody is saying acetaminophen is ineffective, just that it's effects come with hepatotoxicity. A larger dosage of hydrocodone could have the same net analgesic effect without the huge negative effects.
Actually, the linked article is saying exactly that:
"I remember being annoyed that in order to get narcotic pain relief I was being forced to take a hepatotoxin that added little to the pain relieving efficacy of the opiate."
Oxycodone is a very good opioid and, if you aren't abusing it, it is affordable for most people, even if you don't have insurance (http://www.rxassist.org/Search/Prog_Details.cfm?program_Id=1...). But if you need it every day to support your habit, it's too expensive, so vicodin and its friends are the drugs of choice.