Are these people just weak minded? Do they lack inherent ability to make their own decisions and depend on others to rule them (sheep)? Is there some other psychological issue there that makes them more likely for total commitment than others?
I suspect that prior abuse has something to do with it. Some are born into a culture of abuse and don't even realize that another way of life is possible.
If a person is taught by life experience that some human higher than themselves is always right, that to voice different thoughts is sure to be punished, that to act on one's own initiative means emotional and physical torture, then yes, such people will be much more easily controlled by WT policies if they should become JW's.
They're not weak-minded, not at all, nor do they lack inate abilities. They just haven't come up (yet) with a way to escape their current situation. It takes time and exposure to another life course before an abused person can make a successful transition to a more fulfilling way of life.
Never give up hope.