Man, what a thought provoking thread!
I say to each his own, including the youngster. It is hard to drink beer while using my tractor but I have had a couple before mowing before. Definitely after.
The weather plays a role too. When it is blazing hot I just want water and when it is freezing cold, the last thing I want is a beer. Having a few after working hard is very satisfying. Plus, like others have said, I start to get lazy if I start drinking beer. It is kind of a reward to work harder and finish faster! Plus, beer makes me pee all the time.