I used one for years when I had a garden - it caught rainwater from the gutters, and was higher than the garden, so you could get a siphon going to water the garden with a hose.
Someone should tell the people in Bermuda their rainwater does not belong to them - that is all they have for fresh water, every home collects it from their roof into a cistern.
ETA - just had a vision of little kids in the winter, sticking their tongues out to catch snowflakes, and some gov't official saying "Spit that out!"