Limiting fat and protein in favor of carbs in one’s diet is a good example. This bad advice lead to an obesity epidemic that has killed millions of people.
As it stands, I am very skeptical that you could find any such evidence.
The way to change consensus is evidence-based advocacy by experts, not idle speculation by the domain-uneducated.
Without the discussion many of the topis scientist study and figure out the truth would never have happened.
We need the conversations and even controversy help decide where we spend the resource of what scientist study.
edit: gatekeeping
The funding to eventually overturn this bad science was suppressed at mainstream institutions and had to be obtained from the very outsiders you condemn. Phrenology and scientific racism were embraved by the experts for decades. Lucky for us, people didn't follow your advice then.