Never met any such rational and well informed people. How could all fat possibly be bad? Cellular and organellar membranes all over the human body (and any other organism on this planet) are built from fat [1].
These membranes conduct neural signals, release and respond to hormones, participate in immune response and facilitate all types of metabolism by enabling cell and organellum compartmentalization.
Some of the fatty acids necessary for these functions are not even produced by the human body [2] and therefore must be ingested.
I think the real question people ask is not about whether fat is bad or not, but about the benefits and risks of relative proportions of fat and other nutrients.
These membranes conduct neural signals, release and respond to hormones, participate in immune response and facilitate all types of metabolism by enabling cell and organellum compartmentalization.
Some of the fatty acids necessary for these functions are not even produced by the human body [2] and therefore must be ingested.
I think the real question people ask is not about whether fat is bad or not, but about the benefits and risks of relative proportions of fat and other nutrients.
[1] https://en.wikipedia.org/wiki/Cell_membrane [2] https://en.wikipedia.org/wiki/Essential_fatty_acid