The archaeologists who conjectured about this were not horsemen. I can't imagine how anybody could get horses to take "a lot of alcohol," enough to make them nearly unconscious. You can get some horses to occasionally drink a bottle of beer, but not "a lot of alcohol" as the article suggests.
"You can get some horses to occasionally drink a bottle of beer, but not "a lot of alcohol" as the article suggests."
When I was a kid, we had a quarter-horse named Dutchess. She would drink beer whenever she could get it. My dad and some of his buddies had a keg one day, and she drank half of it before they realized they were drunker than she was, but not as drunk as they wanted to be, and wouldn't get that way if they kept giving her beer. I could buy it quite easily. Especially if you had "fortified" beer.