Like the initiation rites for fraternities or sororities, the pain is the point. The reason behind this is that a commonly shared embarrassing experience creates intimacy and loyalty.
I'm more inclined to accept this theory over others including the one from the article, because it can explain many rules observable in the drinking culture (at least in Northern China).
1. It's rude to reject an invitation to drink together from a person with higher status.
2. When many people drink together, the more you drink, the greater respect you show to others.
3. As a consequence, the person with higher status can choose to drink less than others, or they can choose to drink the same to show greater respect.
4. People with lower status should proactively invite people with higher status to drink, in the order of their status.
Therefore, in a typical drinking party (饭局), the people with lower status usually drink the most, often to the point of being unconscious or causing a scene, and that would show their loyalty.
This was part of the job for government officials and those who work with them. And people could genuinely get pretty sick from alcohol consumption. Death from drinking is not uncommon. There was even a debate on how to divy up the legal punishment to the people at the same table when this occurred. And it's not a theoretical sophistication at all.
Luckily, Xi has banned this as part of his anti-corruption campaign (八项规定, the Eight Rules), so it's less of an issue now.
Furthermore, young people in China have moved passed the drinking culture as well. Back in the university, one can choose whether to drink or not, and when one drinks, any amount to their personal preference is acceptable.
I should add that I don't drink at all, but I was often in a situation where I was supposed to drink and got asked a lot. That's why I sought an explanation for the drinking culture and I suspect that many people who participate in this culture can't explain it explicitly.