Sure. for catalogs with many categories, you might want to have different search facets for different types of products. For instance, with televisions, you could have a facet for screen size. However for speakers, that facet makes no sense, and you might want a facet for maximum wattage.
The idea that I am asking about is a method to dynamically identify and create these different facets by common attributes in a category. For a catalog with thousands of different categories, manual facet creation is potentially too much effort. The link I supplied demonstrates how dynamic facet creation might be implemented with algolia.