Only extremely light systems would/could be effected by this issue. After all, Have you ever seen a power supply idle at 0.6 watts?
1 or 2 high performance hard drives would fix the issue as they would make up any required minimums for you.
If a system was lets say mitx(since the boards take even less power) with no video card(even an AMD card with zerocore takes more power than the cpu in its dead idle state in this case) and add a single SSD. You may be able to hit the limits on some power supplies, but a majority of newer power supplies are efficient and fully functional at low loads.
My ITX system can idle as low as about 21 watts if I trust APC's software for my UPS. So the DC load is even lower and I am willing to bet it is not that efficient at these loads. No problems for the current 300 watt FSP in the system.