Problem in the 70s was trans fats. Now they're no longer a risk, replacing butter with margarine is a solid evidence-based decision for one's health (though not so much for one's enjoyment!).

Hang on, there's such a thing as non-trans margarine? Sheesh, I'm behind the times.

(And really, margarine can be plenty tasty. As a kid I actually preferred it to butter for some reason.)

Literally all of them now (in the US and UK at least). Trans fats in industrially produced foods are banned.

Not entirely, pastry still has lots of trans fats, but they're probably essential.

Okay, the cereal commercials in the 1980s: they would have some ridiculous cartoon mascot and sing a catchy jingle about their sugary cereal treats, and then at the end, they were legally required to say "Part of this balanced breakfast" while displaying a tray including some real fruit, toast, perhaps a glass of orange juice.

https://youtu.be/reLIPoZQZ-8?si=lLXfhsdm89zlOWsI

Those commercials played multiple times a day in my childhood, and they never failed to piss me off, because they clearly demonstrated that "milk and a box of Chex" was not by any means a "balanced breakfast".