Wildly inaccurate. What the article is doing is comparing the 40 year return at 7% to a 40 year return at 7% minus 2% management fees, and noting that your total return in the second case is about half as much as your total return in the second case.

Of course all that tells you is that it's stupid to pay 2% management fees if you can get the same return with lower management fees. That's obvious. Whether you can get the same return by yourself is a separate issue. Now, in the long run, your typical investor is going to get the same return (pre-fees) with active management with 2% fees as he does with an index fund at 0.1% fees, hence he's going to come out ahead using an index fund. But at least in theory what Wall Street is selling you here is better return than what you could make on an index fund.

In a way, it's the same as every other product that drives the modern economy. They're selling you an idea (in this case, that active management will yield higher returns). In reality, its the same cheap Chinese crap everyone else is selling.