Neither fiction inspiration nor travel guides are the only source of motivation to travel; the desire to discover can arise from anywhere.
Let's forget hierarchy for a moment, because a childhood memory or an impromptu conversation can be more powerful than a novel.
The role of guides is to materialize this desire, to provide practical information so that the dream becomes reality, not to evoke it.
A patient might be inspired to visit Italy after watching a report on Mediterranean cuisine, and only then consult a guide to find the best markets.
The true utility lies in the ability to transform a diffuse idea into a plannable travel project, regardless of its initial source.