I did not go to the source article, but is it not possible that these boats were not in long-term storage and are just stored whenever not being used. Perhaps the owner uses it every other weekend.
I looked but couldn’t determine what kind of faciltity this is. The term “storage” usually implies renting space for something for a period of time. People who do not have wet slips typically try to keep their boats in or near a marina, or perhaps at home if they have space. Boats sometimes sit for long periods of inactivity due to owner issues such as health problems, financial problems, business travel, divorse situations, etc.
But yes, it is possible that maybe this facility was used for parking a boat in between outings. It would be a challenge to steal and store one boat much less three so this is an interesting case. Stealing a boat with an unknown maintenance history is risky in itself! ;)