Groups organize to the measure its possible for them to organize. Of who can trust each other under what conditions.
A lot of things play a hand in here, the dumbar number, familiar bloodlines, blackmail clubs, MKUltra and so on.
If they can turn someone from your organization, your organization now belongs to another organization.
What is the ultimate loyalty bound?
And to not vaguepost, the ultimate loyalty bound is: Ritualistic implanted secondary/fragmented multiple personalities whose the individual does not control and an immune master controls.