The author was never a traveler, he was an expert in travel literature.
Rather than telling other people's travels, La Porte chooses another formula: he introduces himself as "the Traveler", and, writing letters from his places of residence to a certain "Madame", uses Traveler Relations, real those, to furnish her souvenirs in her dressing-gown.
And he pepper his story of the meeting of some other characters.
And due to its objectivity, many historians have cited him as a primary source, when his text is of secondary or referential source.