Chemically, lecithin is a an "amphiphilic" emulsifier. Amphiphilic means it can dissolve in either water or oil, and can also emulsify things that are not normally water soluble. The most common amphiphilic emulsifier everyone is familiar with is soap. Since kavalactones are not very water soluble, the idea is that lecithin ought to make them more so. Things like coconut and other oils don't have the emulsifying properties of lecithin, but kavalactones are more soluble in them than in water, so they can be used to increase KL extraction. But then they tend to separate out into a film floating on top, which in my subjective opinion is pretty gross. People here probably talk about coconut oil more than other kinds simply because coconuts are also tropical island things and are associated with kava drinking, although coconut oil is not traditionally used to prepare kava. The purported health benefits of coconut oil versus other saturated fats are debatable, and that debate is probably outside the scope of this forum..