It is all about dualism. With ideal components, you can make an ideal SMPS type voltage converter (= using an inductor to do the work). You can't make an ideal voltage converter using switched (flying) capacitors. That is not the universe being unfair to capacitors: you can make an ideal current converter using switched capacitors, which is not possible using inductors.
I can't do the math out of my head, but the problem with capacitors and a voltage source is like this: take a voltage source with a certain source impedance (= series resistor). Connect a capacitor to it and load it for an infinite time (any finite time will do too). Calculate the amount of energy lost in the series resistor as a function of its resistance. Now mathematically take the limit of that formula twoards zero resistance. You will find that the energy loss will stay the same. Intuitively this is because a smaller resistor causes a higher initial loading current, and hence a higher RI2 loss.
You can't connect an ideal voltage source to a capacitor, because that would result in an infinite current which is impossible in itself and would cause an infinite magnetic field which would destroy the universe (just kidding, remember this is the management summary). But you can approach this ideal as closely as you like, and the result will still be the same: a fixed amount of energy is lost while charging the capacitor. Hence: sorry boss, no ideal flying capacitor voltage converter.