This is true. However, not a concern for me. Chameleons live in harmony with parasites in the wild. Providing your cham with optimum conditions, parasites should not be a problem if the animal is in good health. Also frequent fecals can tell if your cham has parasites and you can treat accordingly if wanted.
I see you are new and still getting your research in. Honestly, there are already enough members on here who repeat what they have read without experience in dealing with a certain situation. I hate to sound rude but we dont need another fly by night expert. Its best to stick with giving advice from experience not what you read, which isnt always in the right either.
Not to mention commercially bought insects can just as easily carry parasites as wild caughts.
I am all for feeding WC insects as long as they are from a pesticide free area and you know the insect is not poisonous or feeding from "toxic" plants (which is a whole other can of worms that I am not going to get into). WC insects can give your cham nutrition it otherwise wouldnt get from commercial or home made gutloads.