No internet, no Amazon to find ex-JW books, no Facebook to link up with ex-JW groups. Still people find it so hard to leave.
Actually In the 5 years prior to 1975, the number of publishers was increasing at an average of 15% per year. Now Jehovah's witnesses are increasing at about 2% per year. So people are leaving by the truck loads in a manner of speaking.
The experiences you read about, regarding people having a hard time leaving the WT are going through a process. Like any other process, the more you put into researching, the quicker a person gets to the point where it won't matter who he/she leaves behind. Some because of family and work don't have as much time to research, so it take longer to build up the fortitude to leave. Others with very little family or retired have more time to research and are gone within a year.