Short answer:Because it’s there.
Long and wildly tangential answer found in an old blue book answer form from Introduction to Literature (oddly enough the question it was answering was about the role of the unreliable narrator in Jeff Vandermeer’s novel, Shriek: An Afterword):
Beer makes the world go round. Beer is mankind’s penultimate achievement (surpassed only by going to the moon. Nothing’s cooler than the fact people have been on the moon). Beer is responsible for 75% of all hyperbolic statements, 45% of all made up statistics, and a full 86% of all self referential jokes.
In other words, beer is good.
Of course, so are music, food, fishing, and a myriad of other subjects. So why beer?
Way back when, somebody accidentally left their porridge out. They came back a several days later, and ate it. Usually that sort of thing had one of three results: Death, illness, or nothing. This time two much more pleasant results were achieved: A solid buzz, and the birth of beer. There is some evidence that there was a third result, a switch from hunter\gatherer culture to an agrarian lifestyle. Which, according to Sid Meyer, caused a race to literacy so you could build the Great Library, and mooch scientific advancements off of the computer controlled players. Not only does beer taste good, it’s partially responsible for civilization.
Eventually, people figured out how to reproduce this happy accident. They switched from accidentally leaving porridge out to purposely soaking loaves of a stale barley bread. We know how they did it, because the first known recipe describes the process in a prayer to the Sumerian Beer goddess. Back then, chances are you only got to try your locally made magic bread drink. Now, I can walk 10 min. to a corner liquor store and buy magic bread drink from any continent except that cold one with the penguins, some of which are so different from each other they almost seem like different things entirely.
So, we’ve got something that’s good, partially responsible for civilization, has a wide variety of styles, and makes the imbiber more verbose. That’s why beer.