To be fair, plane crashes are themselves quite rare. The person you're responding to doesn't have any evidence for those specific failures, but there must have been at least one instance of catastrophic failure or gross pilot error.

You're right they shouldn't be speculating based on nothing, it's just that multiple catastrophic failures aren't that outlandish if we know there's probably been at least one (i.e. the plane crashed).

That is typically why planes crash. If one thing goes wrong, it can probably be handled. If everything goes wrong, the results can be disastrous.

I am not sure what happened in this case. The plane was losing 7000 feet per minute at the end. I am not sure if a 767 in a stall loses altitude that quickly, but if weight shifted aft then the wings certainly wouldn't be generating lift. But would it not self-correct after a while? I have no idea.

The fact that the plane crashed and that there’s no trace of oil slicks in the water.

That says nothing about the distribution of the packages. That's pure speculation.