With the caveat that I haven't seen the insurance policies, I'm pretty sure the insurance company denied the claim because property and casualty policies insure against sudden acts of God types of events, such as hurricanes, earthquakes and windstorms, and they are specifically written to exclude coverage for damages that occur gradually and incrementally over a long period of time.
It would be the same as if you had a leaky rook and over a period of ten to fifteen years water had seeped inside that walls of your house and rotted the studs. If you made a claim on your policy it would likely be denied because the damage didn't occur as the results of a sudden and catastrophic event.
IOW, if a tree falls on your house in a windstorm your insurance pays for a new roof. If your roof falls apart gradually over a period of ten to fifteen years, your insurance isn't going to pay you for a new roof. I would be surprised if the same didn't apply in this case, as property and casualty insurers to go great lengths in their policies to exclude from coverage precisely this type of situation unless someone specifically purchases coverage for non-sudden events. And if they had purchased such coverage - assuming it were even available - they would have paid a correspondingly higher premium, all the while that owners have been screaming that annual fees were already outrageously high.