Not to beleaguer this angle but to answer the question. Most events have a human element, and there are two broad scenarios here - either it was accidental, or it was purposeful. Assuming the latter, then there must've been a reason to make the plane completely disappear w/o a trace. If the purpose was to get attention/make a point, if the plane is never found would go down in history as one large unsolved mystery. But as you pointed out, time and currents would disperse debris, so landing it in water is a moot, unless whoever did it was planning on surviving and being picked up somewhere. Looking at the problem from the mind of whoever did it instead of looking at the (potentially incorrect) data points we are getting. Thanks for the insight though.