The people who promoted the open society in the last century, and continue to promote it today, do so as outsiders. They look at the organic communities and societies of the West and simply see collections of people. The alien cannot see or understand the reciprocal obligations and duties that hold the community together. These are only obvious to the people inside, because it is what holds them together. The outsider only sees the benefits of membership, not what defines it.
Read that last line again: The outsider only sees the benefits of membership, not what defines it.
Emphasis added. Leftists think that the ‘benefits’ will still exist AFTER they have destroyed the society by, say, open borders and illegal immigration. See California.
Source: Open and Closed