Not true. Switch mode power supplies (typical PC PSU) will blow up with no load. The fan counts as a load. Take out the fan and watch the voltage go up until it smokes. I know, I fix the things and have blown up many with no load. Switch mode means it takes the AC in, converts it to DC, then switches it to high voltage, high frequency, then steps it back down again, then converts back to DC. This is far more efficient as transformers don't perform as well at lower frequencies and lower voltages.
It's not like mains power or a battery which can sit around doing nothing. I would say from experience that one in four can be blown up in this way, most likely not much to do with cheapness or quality of design as just about every PSU brand (nearly every brand is different) has a different circuit for it, and even the same brands scarcely keep the same circuit for long as they always source the cheapest components available at the time.
The underlying technology has hardly changed since the the days of XT computers, nothing really "modern" about it. You won't find any more modern fancy components in newer PSU's.