I know that I was taught that the vials of Revelation 16 are not really vials but actually bowls, but I just had to try some experiments.
I filled some bowls all the way up with water. Then I tried walking with them from one place to another, since I cannot fly with them from one place to another, and they always spilled some, no matter how careful I was. Then I tried to pour the water from the bowls. The water wrapped along the sides and the back of the bowl, and came down over a large area of the bowl, not a narrow stream. So it was essentially impossible to aim the pouring, to pour upon a certain spot.
In my experiments, it appeared that filled bowls  are like the worst way to transport liquid, and also like the worst way to pour from. I was taught that the ancient Greek word had been used back then for bowl, and maybe that is so, but it sure seems, at least to me, that in our language, using the word, "bowl" would not make sense at all.
Vials usually have a taller and narrower neck, which make them very suitable for transporting when they're full, and very suitable for pouring.