Those Houses have been there for years.
The outside shot of that Deck before the collapse make it look like it was original the House. The exterior upkeep for that House was lacking.
That Deck should have been able to support much more weight than those 15 Partygoers.
From the YT video, the deck looks to be way out of code. You can see that the house next door has a deck in poor condition too. The pillars look totally inadequate, and that’s not taking into account the years of ocean spray it has gotten. Amazing that homeowners weren’t warned. In my neck of the woods, you can’t get a contractor to repair deck - it can only be replaced due to code.