1.(of an appearance) Fail to give a true notion or impression of (something); disguise or contradict: "his alert manner belied his years".
2.Fail to fulfill or justify (a claim or expectation); betray.
People look at it and think it's just a type of cable, without realising that it's the infrastructure that the entire networking industry relies upon. I score this as a correct usage of the word. Also, people assume that things going on behind closed doors must be more complex than they understand, so they imagine there must be something more complex than ethernet under the hood.