I think that part of the essay might have been about how addressing him as Mr. Firstname is actually more formal than Mr. Lastname, even though Firstname is not his family name

Could it be Turkish? Just stumbled on this section on the Wikipedia article on mononyms

Surnames were introduced in Turkey only after World War I, by the country’s first president, Mustafa Kemal Atatürk, as part of his Westernization and modernization programs. Common people can be addressed semi-formally by their given name plus the title Bey or Hanım (without surname), whereas politicians are often known by surname only (Ecevit, Demirel).