Cop out wtf lol. It's not a scifi show. The disappearance is merely the catalyst to introduce you to The Leftovers world where everyone is fucked up. The story they are trying to tell is how people deal with loss differently. Attempting to explain what would cause 2% of the population to disappear would need some kind of supernatural explanation and that doesn't work in the world they have created. It's very much grounded in reality. The parts of the show that shock the audience have nothing to do with the disappearance itself. The shocking parts are the decisions people made because of it such as joining a cult, leaving a family behind, giving up speaking, etc. Nothing supernatural.Having a lot of people disappear but not explaining why, or even attempting, is a cop out and doesn't appeal to me. At that point it's just stuff happening to shock the audience with no real underlying reason why.