That was actually something prompted by a post on +Gianni Vacca blog. I like him a lot, and owe him and his "The Celestial Empire" setting a lot of fun times!
That said, his post that in East Asian settings make it easier to form a party because collectivism s. individualism, really wasn't helpful. To begin with, for most of history, people in Europe were seen as part of a family first, and individuals only after that. That's not so different from Asia. Western myths and stories might be perceived to have a single protagonist, but that's not exactly how it works.
So, how to put different PCs in the same party? Well, it's not any harder than putting them together in an East Asian setting.
Let's see what examples of "natural PC parties" I can come up with.
Students of the same fencing academy/teacher that go drinking together.
Soldiers in the same regimen, assuming roughly equal rank.
A noble, his son or daughter, and their hired guards.
Members of a gang.
Extended family, especially if they have been wronged.
Members of the same Guild, who often practised together as a militia.
of an order.
A Viking expedition, or just members of the same crew.
A knight, his squire, and the mercenaries and conscripts that are just necessary to keep the nobles from encirclement.
A noble and his retinue, including advisors, heirs, relatives and suitors for his daughters' hands, acrobats, jugglers and minstrels.
Members of the same occult cabal or heresy.