After 1980 , many Witnesses were more secretive and discreet about questioning Watchtower rules and understanding.
I would have to agree with that Minimus
There appears to be a purge of weak thinking apostates by the GB heads around that time.
More enforcement to distance oneself from DFed ones as well.
This could have come about or caused by the disappointment of 1975 effecting Bethel and throughout the organization when there was an abrupt drop in active participating members.
People were starting to ask questions or critique doctrines such as 1975.
The GB heads were pressed to take action, which resulted in more DFing for apostasy.