I think it's also designed to limit the situation where multiple groups rent cottages, one being water front (ocean or sound) in the same general area. Then they all converge on that one house for parties (you know, the epic, once in a lifetime type).
Our guests certainly have every right to enjoy their beach vacation, and they should - just be respectful - clean your schit up early the following morning, turn the outdoor music/lights down/off after midnight, etc. When some vacationing visitors get near the water they simply go nuts.
One buddy lives next to a McMansion - he installed a zillion watt arena style light that faces the McMansion - when things get too crazy next door he flips that sucker on. He once (pre light install), when the outdoor music was blaring at 2AM, walked into the house, walked up to the top level and turned off the amp - folks passed out everywhere, no one even noticed him.