It is one of numerous religions that use social pressure as a key component. They expect members to limit their association with anyone who is not a member in good standing (with some leeway for those who are not yet baptized but show the propensity to do so). There are many religions that request/require some level of social self-limiting, but few are as strict. The selection criteria is simple- anyone who isn't a JW --or isn't showing genuine interest in becoming one-- is to be avoided socially as much as possible.
It is an unreasonable level of control, and it is unhealthy. It harms families and individuals by placing unnecessary mental and emotional burdens on them.