So a convincing argument with "maps, diagrams and traffic projections" and referencing information on official documents, is ipso facto itself "official"?

Amateurs then must be forced to make unconvinced arguments unless licensed by the state?

It may be that there's a danger of ignorant people being fooled by those who can spout seemingly convincing, technical arguments. But in a democracy, the only defense is to argue against them and educate the populace. Any other course clearly invites the "dictatorship of officialdom", something that has prevailed in many places throughout history.