The circuit board is the load, all those ICs, really busy.
Big Amps, that's what makes using a big switcher worthwhile, not milliamps.
You need a dummy load to test one, but otherwise, right, it's a waste. You don't want to use a board populated with expensive semiconductors as a test load when some resistance will do (lamps!).
It's usually the 5V that requires the minimum load, it varies, but that's around 10% of max rated.