The Dunbar number of about 150 appears to limit the human size of an organization where everyone can know everyone else.
Dunbar's informal definitions (from the 1990's) is "the number of people you would not feel embarrassed about joining uninvited for a drink if you happened to bump into them in a bar.".
For 100 people, there are 100*99= 4,950 possible connections.
For 150 people, there are 150*149= 11,175 possible connections.
For 300 people, there are 300*299= 44,850 possible connections.
For 600 people, there are 600*599= 179,700 possible connections.
As the size of the organization grows, there are many connections that are not made. That is, there are more and more people who do not know other people.
As businesses and related organizations grow above this number, identification badges, etc., are needed.
As churches and related organizations grow above this number, a way is needed to ovoid the feeling of being lost in a crowd.
The number of connections between all possible nodes increases much faster than the number of nodes.
