I cannot speak for the Jehovah's Witnesses or "extreme fundamentalists." But as "Mormon" bishop, I do not deal in punishment; I leave that to God.
On those occasions when a disciplinary council is necessary, its purpose is threefold: (1) to save the soul of the transgressor; (2) to protect the innocent; and (3) to preserve the good name of the Church. At no time is the intent to punish the transgressor.
The situation described in the article is certainly a sad one. Given the facts as presented, I would have counseled the man to stay with his wife and try to save their marriage. However, if the man decided to sue for divorce anyway, I would not have disfellowshipped or excommunicated him. Such a step would be warranted only in cases of serious sins, such as adultery or abuse.
I cannot agree because I find disfellowship or excommunication warranted only in the case of blasphemers of the Holy Spirit of God (defined as atheists...not agnostics).
Somewhere in the period between infancy and childhood, it is my belief that we all come to possess the ability to sin--and that sin is manifested in thought, word or deed. And every adult or age of accountability child, IMHO, sins every day (I know that I do at least). So, where better place is there to confront those sins, as Christ taught us, than a place of worship? It is my understandiing of Christianity also that no one sin can stand out more egregious than another as the literal definition of sin means "missing the mark."
A long time ago, because it seemed to be so family oriented, I attended a meeting and tried to read the Book of Mormon as I wanted to know more about the church. But I gave up somewhere around the middle of the tale and the notion that Joseph Smith (or Angel Moroni) wanted me to believe there were flourishing American civilizations and gleaming cities in America long before the Spanish Conquistadors. That is not a slam at LDS because I still admire the family principles of the church, I just cannot understand some of the tenents.
So my belief about every one sinning is probably far different than yours. But if you kick some one out for sinning (or in the case of historian Fawn Brodie, for writing something the church didn't like) where is he/she to go but to the devil?