Several of the other comments above make sense.
I can imagine that fuel jugs on deck seems benign to most as it is commonly seen on cruising yachts. And in most mild weather I can imagine there is an attitude of "safe and secure."
I have another anecdote with a lesson I learned and will not forget:
I was on a sailboat headed from Hawaii to California. The skipper had about ten 5 gallon plastic fuel jugs lashed to the stanchions forward on the deck. So, up front before the cockpit. These were filled with diesel. Everything seemed secure. Multiple lashings were tight. Caps screwed down tight. Brand new jugs made for this purpose (holding fuel). Standard sizes, all same size. Multiple lines of strong cordage. Seemed OK.
We left the islands and headed north. We were hit by a severe storm with high seas and high winds. The jugs (and boat) took a beating.
During that first night, the jugs began to come loose in their bindings (the cords holding them together on deck). Just a little bit at first and not noticed in the dark.
As the wind was howling and the waves were hit, there was a constant spray coming back to the cockpit. Very wet, very strong wind.
But, the worse thing was the fuel that was mingled with the spray!
It turned out that the vent caps on several of the fuel jugs had popped off (probably after the jugs got hit by a wave). Those little tiny holes that are for venting vapors (or allowing one to pour liquid from the big hole in the jug) allowed a stream of fuel spray to come out in the wind. This flew back into the face of the helmsman (me) and made it very difficult to see (stinging eyes).
So? Uncomfortable? So what?
Well, the fuel also was sprayed on the deck. One of the most slippery things in the world is a wet deck with fuel on it!
The extremely slippery decks were a hazard for days until we could scrub them (after the storm subsided). This meant the decks would be VERY hazardous IF we had to go forward to lower sails etc. I know, because when my watch ended I went forward in the night to try to find a way to secure the loose jugs (this is when I found the vent caps off). Also, securing those little vent caps was impossible at the time as the jugs were coated in fuel too. Plastic coated in fuel makes them very slippery too. Impossible to secure with duct tape or similar, as it would just slide off. Remember, fuel is a form of oil. Oil and water together can be VERY slippery, even on decks with non-skid.
My lesson? Putting fuel jugs on deck requires VERY strong method of securing against movement and VERY secure method of keeping the caps on if the jugs move or are pressed (by a wave or motion).
Live and learn.