I agree with the BASIC idea behind disfellowshipping.
BASIC = what everyone does = you don't agree with me, so I am limiting my association with you. Just what that entails depends on the individual, organization, etc. It could be sitting on the other side of the coffee shop, to disfellowshipping, to issuing a fatwa. Everyone deals with people that don't agree with them.
Do they (JWs) take it too far? Probably. The main problem I have is that the judicial process is so flawed, that you have people like a friend of mine who got bum deals.