The "facebook-esque anecdote" was intended to point out the failings of acting as if scientific institutions are practicing science in a pure, non-biased way and blindly trusting the humans in these institutions to not be subject to corrupting influences. My stepmother's god-like idolatry of the scientific method was conflated with the very flawed humans who were supposed to be using the scientific method.

Your original point is a fair one, but you probably aren't aware of the fact that, on this specific topic, the leading scientists in the human nutrition field were extremely aggressive in crushing all dissenting voices, including destroying the career of a researcher at Harvard who was relegated to obscurity despite later being proven correct.

Dissent against Keys' lipid hypothesis of any form was career suicide in the human nutrition community. The viciousness of the attacks against dissenters was particularly remarkable, due to the fervent belief that undermining the "fat is bad" narrative would kill people.

They were wrong, and your point of view assumes that it's self-correcting over the long-term, so don't argue. In the case of the lipid hypothesis, it wasn't self-correcting at all. It's been a decades long fight to try to get a bunch of smug asshole academics to admit they fucked over the public for decades with their hubris.