Can you name some Christian groups that have 30 to 100 million members and are growing? The vast majority of churches are in decline.
DFing probably keeps some JWs and loses some others. Other groups that disfellowship, such as the Christadelphians, are in decline. JW growth is probably due to a number of factors.
I can’t understand how JW growth can be described as a “disaster”. Churches in the UK, such as the Methodists, Church of England, and Church of Scotland, are losing around 2% to 5% of their membership annually. This trend has been steady or getting worse for the past 40 years or more. Unless the trend improves rapidly, these denominations are set to disappear by around 2050. By contrast, JWs are still growing in the UK, despite the country’s heavy trend toward secularisation. I don’t see how this is in any way a “disaster”. It’s the kind of “disaster” that most other churches would dream about for themselves.