It's not, but when it takes up the majority of your waking life at ~60-80hrs/wk, it's not an unreasonable expectation, especially for the mental well-being of the workers. And so long as the trend continues towards longer work hours, there really doesn't seem to be much of a humane way to deal with that added stress otherwise, despite all the obvious drawbacks you mentioned.
The ideal of course, would be to shorten the workday. Unfortunately, inertia seems to be working very much against that possible solution.
Yes, my observation is the same - the people who spend 60-80hrs at work do take all their socialization into workplace. Meaning they waste time of people who want to work at work and then go home - either because of kids or because of aging relative or because of anything else including hobbies.
The above is one more reason to avoid fun cultural workplaces. They tend to want all of you, not just your work.
Professionalism is what allows you to work together despite being very different people with different interests and personalities.
Fun workplaces tend to discriminate against those who are different on personal level regardless of their actual skills and contributions.