Reconstructing the opposing argument first: it is true that works of fiction can ignite the spark of inspiration for a trip, and that travel guides then serve as a practical materialization of this idea, especially without internet connection.
However, considering guides as merely a sub-part of fictional inspiration seems reductive.
Travel guides are often the first concrete point of contact for discovering a destination, long before a story takes root; they offer a mapping of possibilities.
A good guide, for example, can reveal lesser-known regions of Belgium, like the Ardennes, which would never have been considered without this structured source of information, regardless of any film or book.