I was an ordinary English major back in the day before it became a permanent joke, when the liberal arts were about becoming an informed human being and not about getting a job. So I never went to journalism school. My trade school was a theological seminary, which is a graduate school that presupposes a bachelor's degree.
So I don't know who introduced the question-mark headline. It may have come from a journalism school, or it may have grown out of the cynical, doubting questions tacked on to television reports, more or less suggesting that the reporters themselves hardly believe what they have just reported to us as news.
I have been a fan of Diane Sawyer for as long as she has been on national news, except for this one thing: She will hardly get through a newscast without ruining her authoritative, low-pitched and beautiful speaking voice by raising it to a high-pitched whine reminiscent of a gossipy junior-high girl. It makes her face a visible question mark and her voice an audible one, asking in effect, "Would you BELIEVE this?" My question in response is, "If you didn't want me to believe it, if it isn't news, why did you waste my time telling me?"
Since we watched Diane with Charley Gibson on live television as they anchored Good Morning America on the day the Twin Towers came down, and have watched her before and since interview on camera some of the worst men in the world, we have cause to believe that she isn't dismayed by much of anything. The pose doesn't work for me.
I don't want to blame Diane for anything, so I assign fault to the ABC editors and directors for perpetuating this habit, which would have earned a C- (for effort) when I moonlighted as a night-school teacher one semester.
Whoever invented it, the printed or audible question mark is now commonplace as a cheesy rhetorical device that has nothing to do with the news as such. It is a segue into speculation, baseless controversy, or scandal in which there is no real sin or shame. All of it is easier than reporting, and less boring and apparently more appealing to those who provide the advertising bucks. It also masquerades as news, mostly in the subjunctive mood--about what people may have done or are "reported" as having said.
Okay, I'm speculating. But nobody is paying me big bucks for it, and nobody is calling it news.