I’m third generation on both sides of my family. This was the mid-50’s. Both sets of grandparents were in their mid-20’s, newly married with young children. Coming up out the Great Depression, they were not very educated. They knew little about the Bible and the JWs who came to the door seemed to have all the answers.
I believe the JW teaching of no eternal hellfire torment is an attractive alternative to many other fundamentalist churches who put the “fear of hell” into their adherents.
The disfellowshipping arrangement and blood transfusion ban was freshly introduced not too long before this and my newly converting family likely real didn’t hear about that in their study.
It was a different religion in the 50’s then what it became...why the few people who do convert do so is likely somewhat different than why people converted back then.