There are many actors that want to convince you something bad, is good. Historically, cigarettes, sugar, even cocaine were advertised as healthy, or as better substitutes to things. Hell, even grain is still pushed by industry and government, when low-carb has a lot of evidence backing it.

Guess what happened when we decided "telling people sugar is great for kids" was bad? The government now regulates the information people are provided regarding nutritional content in food.

Speech isn't so easy, which is why the analogy still doesn't work.