Where does Forbes find these writers? That guy who wrote the "arbitrage" article, and this gal. 2% for PPC is bullshit. That would be good for pure organic, but not PPC. PPC for retail should run more like 4 - 7%, and probably more for other industries.
The author doesn't know what she's talking about. PPC has great a ROAS, a lot better than tv or radio, which is why a lot of big companies are investing in ppc. If you read the article she states that a third of respondents spend 21 hours a week managing their campaign, well if that's all the time their spending managing their campaigns then of course they're not going to see a great return.