I'm trying to keep an open mind here... but this is totally pointless, surely!?
If you're building a silent mid-power (300-700W) there are already fanless (or semi-fanless) options available. If you're building some Tri-GPU monster that you want to keep quiet, dissipating the 1200 odd watts of heat from those graphics cards is going to take far noisier fans than those required to handle the ~100 watts worth of heat coming from a top tier PSU.
Am I missing a use-case here?
Actually, I run a custom loop ,(wasn't going for silent when I did), for OC'ing purposes. I have a ton of fans on a huge External Radiator that sits several feet behind and below my PC (behind the desk). All the fans are Low Speed Yate Loons, which were extremely cheap. You can't hear anything running when the PC is on. I think I can hear the PSU fan sometimes, but I'm pretty sure it's just the DVD drive or HDD storage drive running.
I agree, the PSU does not need this at all. My EVGA is extremely quiet and also has an Ecco mode, which I never use. I was just trying to point out to you that dissipating a lot of heat doesn't mean you'll be getting a lot of extra noise with it.