Meaning of "closed social system"

Generally, open systems allow interactions between internal elements and external environment; closed don't.

A fraction more specifically, closed social systems are said to fix individuals in their social position, and presumably, to fit in with the more general definition of open and closed, this occurs not because the system as a whole is closed but because the different social strata are closed.

Closed social systems, imma say, require participants to perform social construction before other types of constructive exchange can occur. Posed like that, sounds like I'm talking China. "Making friends" is required before other types of communication can get off the ground. Projects depend on connection.

But, in China, people can "make friends"? Literally enter the society of others and become connected?

So it's not a closed social system?

How about a purportedly empirical observation?

China used to be very closed, and the people in there were intensely curious about anything new. Then China "opened up". China became pretty easy to get into and start meeting people. Still is, or was, pre-2020. But that curiosity is, well, if not gone, then driven so far underground it's negligible. So, opening up the country and closing up the hearts and minds?