On super yachts there’s large hatches to get tenders (dinghy) in and out like a garage. Some also have swim platform hatches at the water line. If any left open that’s really bad. The videos below also has a comment from someone who’s been in boats by the same company that says there’s a design flaw / feature with a different set of doors that are not for tenders but people (like patio doors) that could slide open when the boat helmed (rocked) in the water spout.
There’s a video of a large sailing yacht (45m, compared to Bayesian which was 56m IIRC) in New Zealand getting rocked over almost 90 deg in the linked videos as well, that really shows what’s possible in the power of a storm. That boat doesn’t have a folding keel though so it righted itself right away.
Also, the builders may that the mast was much larger than it should be for bragging rights essentially