I'd say you have a point, and I think that the answer is heavily tied up in the "missing white woman" phenomenon, and the role of the press (professional as well as amateur) in that. In Duggar's case, he had already confessed to behavior very close to what he is accused of, so it is more reasonable to believe he is a recidivist, and the FBI *had* charged him with the crime when the story broke, but I think the key point is that photos of his alleged victims were not plastered all over the internet to draw sympathy. While child pornography is not a victimless crime, most of the time the victims do not have a public face, and thus the likelihood of mob incitement is less. Also, it doesn't involve a death, which is key. Look at the Larry Nassar case. Plenty of people defended discounting the testimony of minors, and plenty of others were out for blood, but the victims still grew up and still have lives, and some people think that's a mitigating factor, despite the fact that the victims have been actively tortured by the ongoing hearings in this case for YEARS.