Is it because presenters believe news isn't authentic unless it is upsetting? Could it be that they're not really warning us at all, but showing off and that their real message is: look at how upsetting this report is, it must be real news.
And isn't there also a problem for the audience if, after the warning is delivered, we don't get upset - or don't get upset enough? Does that make us bad people? The expectation is clearly that we should be shocked and unsettled the moment a presenter tells us to be, but most of us would rather rely on our emotions rather than Krishnan Guru-Murthy perched on the edge of a desk suggesting: "Here is the news, you will now starting crying."
Not that it's Krishnan Guru-Murthy's fault. When he delivered the usual warning ahead of Unreported World (Channel 4, Friday, 7.20pm) he was just doing what everyone else does. He was proud of his report on women's rights in Afghanistan … and quite right too. It was an excellent programme.
The report began with 22-year-old Zarghona who told Guru-Murthy what happened when she refused to marry the man her family had chosen for her. Zarghona's father took her to a deserted spot and began to stab her with a knife. She ran through the grim checklist: first, he stabbed her in the back, then in the stomach, then the side, and then, as she prayed, he slit her throat and covered her with a sheet.
Astonishingly, Zarghona survived and now wants to show what is happening in the name of family honour. "They said I had dishonoured them," she said, "but I am a woman with dignity, self-respect and honour. I never wish for another Afghan woman to go through this."
The point of Guru-Murthy's report was that other women absolutely will go through this and that women's rights in Afghanistan are at risk of going into reverse. Four years ago, there was hope women could begin to defy the old Taliban strictures and take jobs and go to college. There was also some progress on domestic violence, with President Karzai passing a decree that beating women was wrong.
The problem now is that the religious conservatives want those advances reversed. They see women's shelters as immoral dens run by foreigners. They want women back in their family homes, said Guru-Murthy, living with the men who attacked them in the first place.
Which meant that there were two warnings in Guru-Murthy's programme - one telling us we might get upset, and another, much more serious one. Women's rights, said Guru-Murthy, were supposed to be the great legacy of the war, but as international forces pull out and the country tries to find a settlement with the Taliban, the religious hardliners are back in play.