^ So what you're saying is, someone actually *believed* the lie that "small caps in parallel with big = good"?
Power supplies are impedance networks, just like any other. They are generally intended for much lower impedances, but their structures nonetheless resemble transmission lines, and therefore posses characteristic impedance, resonances and cutoff frequencies.
Best design is had, not by piling disparate caps together and praying that they work, but by careful design, taking into account the body length, trace length, via length and so on between capacitors, component pins, and the surrounding circuit.
Most often, a bulk capacitor is desirable, for no other reason than its ESR. Certainly not for energy storage, or minimal impedance. This is the biggest benefit to tantalum capacitors: the ESR is well controlled, and stable against temperature change, so the power supply network's frequency response can likewise be designed for stable performance.
Tim