We already left the land of reason far behind by the time OP implied hamburgers and milkshakes give people cancer.
I don't know what else to tell you. Except maybe that if one gets this single concept, that quantities matter, it becomes immediately apparent why most of the "healthy eating" / fitness fads is just pure bullshit.
Seed oils are not as bad as painted but some caution is needed given for instance the industrial processes used to bring them to market sometimes. Plus the way the oils are cooked when they create free radicals. This is not nonsense.