I think the issue is not so black and white, speaking from 25 years in Deale.
A few observations: some boat insurance policies require a specific ice/snow rider or you may not be covered. I think Boat/US policies provide automatic coverage for Maryland, but not further north.
This winter offers a pretty good example of why it's a good idea to get hauled out over the winter. Although our recent snow storms/blizzards are rare, they do happen. The one time I left my boat in the water over winter we, of course, had a monster snow storm. It was really difficult to just get to my marina. Once there, I had to trudge through snow above my knees. Getting down the pier was pretty risky. Once at the boat, the lines were frozen and the boat could not be pulled close enough to board safely. Finally, the snow/ice on the boat was frozen solid by that time and there would not have been a way to remove it anyway.
I just can't see how it can be worth it to anyone in a state that gets significant snow or ice to stay in the water over the winter if haul-out is available.
The only season I had damage I was on the hard at Herrington Harbor. The snow load you saw can push props up through the hull if the blocking is not perfect, and that year many boats came off their stands. I think a boat in the water was far safer. The roof falling was certainly devastating,
but I see nothing the picture to suggest a well-founded sailboat would have been harmed.
Note that all of the boats were power boats. My neighbor sunk this winter - powerboat. They have large cockpits that often drain to the bilge, rather than scuppers. Bilge pumps fail. Also, some have poorly designed exaust systems with inadequate protection if the pipes are pushed under.
I got a good load on my boat too, over 3' at the peak. All it did was settle in the water about 2 inches. Nice even support, no pressure from the stands. I cranked up the heaters an spent the night (I did have to dig the smoke stack out a bit). The docks were deep, but ice climbing is my other hobby! Very quiet.
Freeze damage is general non-existent for a boat in the water, because the cabin temperature is moderated by the water. I have never had a bottle of water freeze solid while in the water, though on very cold nights I have seen some minor ice. I do winterize, to some extent. I run a bubbler when there is thick ice.
The Sassafras is freshwater. The ice formation is MUCH worse than the salty parts of the Bay. I would have to think hard about that myself. Certainly, I would have a bubbler in.
A post on the subject.
http://sail-delmarva.blogspot.com/search?q=winter+sailing+ice
What is required is forethought as to what can happen in the worst conditions.
I was sailing in January. I will go out again next weekend, I think. I like winter cruising.