One reason for Key’s success was good old-fashioned magical thinking. It is easy to look at a pool of congealed grease on a dinner-plate and think “the fats I eat must be pooling on the insides of my arteries”.
Another reason is the foundational assumption in public-health that it is better to burden people with some dietary advice, any advice, even if it’s wrong, because they might start losing faith in the system if you gave them no advice at all.
James Lefanu has been pushing back against the “fat = heart attack” paradigm for at least 20 years. With only limited success.
