Being in the registry isolates a person from the society with its inherent restrictions in terms of the place to live, find work, or social interactions, even a place of worship like churches.
Loneliness or isolation is the cause of much of issues or problems. When people are alone they are more prone to be depressed, consequently their mind is at the mercy of whatever thoughts come to the mind. Also without family member/s or loved ones around, there is a lack of that circle of checks and balance which we all need in terms of guidance or support system.
So remove all that which makes us connected human beings and you end up with detached asocial beings which is what the sex offender registry does.