I don’t fully understand it but Big Clive explained it once while tearing one of them apart.

Erm… yeah, i’m not en electrical engineer but slapping capacitors on things still increases power use slightly because capacitors have losses themselves. So that doesn’t make any sense. I get the smoothing out voltage side but voltage and amps can change as much as they want but the watts is always constant. So I still don’t see anything they do can reduce the wattage.

But i’m an uneducated idiot so who knows!