Similes on the Internet have explanations.

We searched the Internet for expressions linking topics, such as crime, and vehicles, such as disease, as similes (crime is like a disease) and as metaphors (crime is a disease). We counted the number of times the expressions were accompanied by explanations (crime is like a disease because it spreads by direct personal influence). Similes were more likely than metaphors to be accompanied by explanations. Similes may be preferred if a writer wants to express an out-of-the-ordinary relation between the topic and the vehicle.