If your objective is to try and provide people with the lowest hanging heuristic for how to avoid unwanted weight gain, avoiding high fat foods is a pretty good candidate, since fat has the highest caloric content per gram (9) when compared to protiens and carbs (4). This appears to be the traditional view that the crazy government is trying to shove down our throats, so to speak.

As a historical claim, I believe that this is false. The opposition to consuming fat is primarily about correlation with heart disease. Certainly none of the examples of government advice in this post are about weight loss.

Along come the carb-cutting people. My hypothesis is that the general rationale for this movement was the recognition that the average American diet was made up of some huge % of carbs (>50% of caloric intake) and so the simple math of avoiding carbs, even if you upped your fat intake, would ensure your daily average caloric intake went down.

They wrote down their reasons and this certainly isn't any of reasons that Atkins gives.