Hah, I've counted 10+ different intelligent(?) guesses in the replies.
My handy heuristic for headlines like this: Is it a scary new trend that means something or did other factors suppressing its natural emergence decline? Or is it a matter of observation?
A recent real-world example was the detection of two different objects entering the solar system. The naive speculation was "they came on the same plane, so they must be alien!" But the reality is more mundane: the new detection method that found them, while flexible, started by looking at that plane. So of course both objects it detected were on that plane.
Unfortunately, that doesn't seem the be the case here, and the article goes into this. Deaths due to colorectal cancer under 50 simply used to be incredibly uncommon. Younger people were simply not screened for it. The rise is not solely relative to other forms of death, but in absolute terms has increased.
I'd agree that really smart and plausible theories can turn out to be incorrect. But, I'm not sure I'd necessarily agree that plausible guesses aren't doing anyone any good. So long as theory is otherwise healthy (eg: eat vegetables and exercise regularly) then they might be doing some accidental good, and if they turn out to be correct, give people a bit of a head start.