The reason is that the EDL protocol was invented for linear (tape based) edit suites and is limited only to very simplistic numeric descriptions of things that are possible on that type of equipment. In a linear edit suite there is no such thing as multiple video tracks, clip names, plug ins…etc.
Just make multiple copies of your timeline. One with each of the individual video tracks. Export an EDL from each. Remember, almost no effects info will translate using this method.