When rounds are not expected, it feels really nice when someone unexpectedly buys everyone a round. Similarly, it feels delightfully magnanimous to buy a round; makes you feel like a King.
I can see how it quickly loses its charm once it’s an expected transaction to honor.
It’s a much more intimate experience and we formed relationships with people without even being able to speak at a conversational level.
This means that every time you want to sip your drink you have to entertain this needless protocol: identify someone around the table - preferably someone you have yet to drink with - say cheers (translation required), and sometimes drink all of the 60 mL cup at once. You should also keep a checklist of who you have and haven't drunk with. The more political, the greater the need to move around the table at random intervals, shake hands, and drink. This is a demonstration often devoid of meaning.
If it's a real party it can be fun to bottoms-up all the drinks. For a more relaxed meal & conversation setting (my preference), as an outsider this is uncomfortable. It ruins the slow enjoyment of expensive alcohol. Why can't I sip my own damn drink with my meal?!
Also as someone who drinks a lot less as I get older, I lately find myself not drinking at all at these events, because there is no middle ground.
It was totally acceptable to sip a drink. If I was empty and needed a refill I would simply take the shared container (650ml beer bottle, tea pot, etc.) and first refill someone or everyone’s drink, empty or not. Essentially the personal containers were bottomless.
I never felt an obligation to refill a specific person’s drink. But that situation never really came up because everyone eventually is the person initiating the refills.
It’s possible I was offending a lot of people. In fact it is likely. They were certainly generous enough to not say so however.
When I used to go to the pub with my cricket team the person who scored the highest that day would shout the group. Or if you'd won big on the poker machines etc then it would be your shout.