lot's (maybe most) of families either don't drink, avoid getting get drunk, or at least find getting drunk shameful at gatherings, and for most people their circle of friends can't meet on thanksgiving because each of them are stuck with their own separate families all day making coordinating a party hard.  it's not so much an actual national tradition as much as something lot's of people do because it makes sense.  the fact that you can coordinate your friends and families to one place is an anomaly.
United States