What do you mean? These vehicles only exist if investors buy into them. Are you saying they were "fooled" by buying these investments?
Their existence is not a secret, which is why those journalists were able to find them and add them up. These aren't hidden secrets being hidden from investors.
I see a lot of theories that this is being done to prop up stock prices by hiding debt and making the balance sheet look better, but large investors understand these financial engineering operations and factor it into their decisions to buy and sell stock.
I do think it's funny that so many people think these reporters have uncovered a scandalous secret that all of the investors missed. The way the stock prices didn't collapse after that reporting is a good clue that the investors in these companies were already aware of the situations.