Perhaps it's because universities are big business. Sure they're state run or nonprofit, but many faculty and administrators make comfortable salaries that they want to hang on to in the face of competition and falling college-age population. The chance to party and get drunk is a big draw for many college-bound teens. 80% of U.S. college students drink and half are binge drinkers. Most universities need to attract those students to stay in business.
Dartmouth College, an Ivy League school in New Hampshire, is in the news these days because its binge-drinking fraternity system is drawing criticism, but most schools are not far from it. My son went to Cornell where drinking was also rampant.
Dartmouth is famous for its boozy fraternity system. Through hazing and alcohol use, fraternities foster multi-generational loyalties that help keep the college going. Would Dartmouth even exist without alcohol? I don't know but it's at least questionable.
Universities will tell you that their students are adults. Though technically true, it's a very loose definition of the term. They will tell you that they can't enforce rules about drinking, though they seem to be willing and able to enforce rules against offensive speech for example. The fact is, they pander shamelessly to youthful impulses.
Brigham Young University, the Mormon university in Utah, is the obvious exception. It prohibits all alcohol use on religious grounds and aggressively enforces that policy. Are BYU students better educated? No. Are they more successful? No. They are, however, happier.
I've known a number of Mormons in my life and they all seemed strangely happy. It's no mystery. It's not because they wear special underwear or believe stories about the Angel Moroni. It's because they don't use drugs or alcohol, not even caffeine. As a result, their brains function normally, and a normal, unpolluted brain is the first step to finding happiness.
The goal of higher education, though, is not happiness, but success, and alcohol use can perhaps help you to be successful. So maybe it makes sense for schools to accept it as a cornerstone of the educational experience.
Universities want you to be successful and stand ready to help you on your way. If you want to be happy, though, you're on your own. Fortunately, you don't need a degree to find happiness because there's only one thing you really need to learn:
Don't use alcohol.