The lipid hypothesis did it. The idea that fat and dietary cholesterol cause obesity and heart disease.
That's only half the story though. The factually wrong part (fat in == fat deposited). The other part, that is still factually correct and hence a good reason to avoid lard, is that saturated fats absolutely and unequivocally lead to atherosclerosis and coronary artery disease.
I'm surprised how easily the 'bad' fats are getting a free pass in the name of decriminalizing 'fats', in the bleeding-edge of dietary pantheon.