I have wondered this myself. My brother seemed very happy at bethel but the times that I stayed there all the bloody bells ringing to tell you what to do and when to do it would have driven me mad.
When I had to meet up with my siblings to dispose of our parents' house and sort financial matters it occurred to me that they are just not very bright, sad to say. Yet we come from the same gene pool.
There is a lot of truth in the theory that the basis for intelligence may be genetic but it's what you do with it after you're born that counts. They were also very paranoid about everyone we had to deal with from the parish council to house-clearing companies. They seemed to expect to be cheated and treated badly. I'm not sure they could cope with knowing the TTATT and living in the real world.