Well its like this. They will not eat during the actual action of the spawn. That is when both male and female are on the nest and he is milting the eggs as she drops them.
What you were doing was plucking the fathers that guard the eggs and for a time, the young fry. They were not eating what you were tossing at them. They were protecting their nest from invaders. That is why you had such an easy time. It wasn't that you were a great fisherman and discovered something. It only takes seconds for predators that are just waiting for the opportunity for an easy meal.
Like you said, to each their own. Probably about the lowest type of fishing you can do in my book though.