If you've flown in that area of the world you'll realize how congested the waters are. As earlier comments have pointed out, there must literally be thousands of vessels at sea, and hundreds in the area of the last known a/c location. It just boggles the mind that aside from the a/c disappearing without a trace, there have been zero reports that one might expect in such an event from eye/ear witnesses on the ground or at sea.
Puzzling. Sympathies to all the crew and passengers and their loved ones anxiously waiting for any shred of news.