In my experience this is not true. People of all ages would pop off for a pint after work or cut out a little early at many places I've worked. It was never hanging out for hours. It would be like an hour and you would usually just talk about the stuff at work that you're frustrated about. Not everyone would go, but high performers were usually well represented.

I think the demographics of HN would explain why this seems like hollywood fiction when it is/was very normal behavior.