Let's first reconstruct the most charitable argument: it is true that once the destination is chosen, a tourist guide is an invaluable resource for navigating on site, especially in the absence of network.
However, suggesting that this role of guides is a sub-part or a direct consequence of fictional inspiration oversimplifies the traveler's decision process.
Inspiration, whether it comes from a book, a film, or even a conversation, is a distinct step from concrete planning.
Guides are tools for preparation and execution, not mere appendices to the initial spark of desire.
For example, I can be inspired by "The Lord of the Rings" to visit New Zealand, but choosing a Lonely Planet guide is not a "sub-part" of Tolkien; it is a pragmatic decision for travel logistics.