That is the problem.... lack of proper filtering and poor quality component choices (cheap electroylytics and garbage ceramics)... Not all electronic components are created equal. Morover, most "cheap china" knock-off products have lessened component count to save cost.
In a typical scenario, they reverse engineer an existing circuit, and rebuild it, removing filter components, feeback components and sub-circuits to the point where the device still runs, but with fewer components.
For example a true Apple iphone charger is a rather complex and well engineered circuit with a well designed feedback controller, full wave bridge, filtering and output protection. The china knock-offs ($5 each) are a simple single diode rectification with an undersized electrolytic filter cap and not much more. One will never harm you iPhone, the other can easily burn it (or itself) up.
FWIW: I would imagine that Wilson has derived the failure rate he quoted by first hand experience...