There are enough believers in prohibition that recreational drugs have been outlawed for years in the U.S., and it's taking some time to get just marijuana decriminalized in a handful of states. Believers in an alcoholic prohibition specifically? Yes, there are a number of communities that are still dry today. I don't know of any benefits. I think there is less drinking, but more drunk driving and marijuana use.
There's quite a lot of them! I wouldn't mind a sneaky look at what they get up to instead. Not so many in the UK, some strict presbyterians on the Scottish isles and again plenty of political/mainstream support for marijuana prohibition. Nice to see some movement in this area in the US. In my mind the prohibition of marijuana led directly to development of super strength skunkweed which has more mental health side effects in a subset of the users- cf moonshine and blindness during the alcohol prohibition in the US. Excuse my ignorance - but was there a particular trigger for the alcohol prohibition ?
It's been a few years since I had U.S. History, but I think it was a combination of America having a drinking problem since colonial times, religious pressure, and a women's movement against abusive, alcoholic husbands. People in America thought there were too many drunk, non-productive members of society and decided to do something about it. And they didn't sit about arguing over it. Many went right into bars to encourage temperance. One memorable temperance movement figure, Carrie Nation, went into saloons and destroyed liquor bottles with her hatchet. What a way to spread the message, right?