I honestly don't think there's all that much harm in seed oils, PUFAs, sugar, fat or any other food bugbear. There's just tons of freely-available, high energy, cheap food that there wasn't back in the past, and some people are more susceptible to gorging on it than others. Back in the past you had to be rich to afford to eat that much (Henry VIII, who weighed 177kg, had terrible health problems and died at 55). But the average peasant was living off gruel and doing manual labour 365 days a year. Modern person drives to work, spends 10% of their income on as much food as they want, sits at a desk all day - there's no surprise they become obese and sick.