"don't feed them bad feeders"?? It happens. It can even happen when you raise your own. You can make some good guesses, but you can't know for sure where infections like that originate, or where the feeders may have picked up something bad. I'm sure most CB reptiles do have some parasites, because that's just the way life is. I mean, almost 100% of humans are full of all kinds of tiny little parasites living in our guts, and we're all captive-bred, aren't we? If something happens that sets of a population explosion of a reptiles intestinal fauna, it could be the keeper's fault, or it could be the animal's genetics, or it could just be that some pathogen floated through the air, infected that animal for a little while, and lowered its immune system.
Sometimes things like that happen and there was no way to foresee it and prevent it.
Loco, I don't think the problem is our overcomplicating things. I think you like to oversimplify when herpetoculture really isn't as simple as you try to make it out to be. It's not always this way or always that way, etc. That whole k.i.s.s. philosophy is a good starting point, but it doesn't mean that every little thing that pops up in this hobby is cut and dried.