Disfellowshipping and it's shunning accomplishes one major thing: INFORMATION CONTROL. It is said to "keep the Congregation clean" -- a little leaven, ya know how it goes. But the reality is that the primary purpose is that it prevents most active JWs from conversing with those who have expressed doubts, or worse, have challenged the Biblical basis of JW doctrine.
When any JW begins to doubt any of their long-held beliefs, we here know it usually leads to researching (since now it is easy to do anonymously online), which leads the person to jw.facts or jwsurvey or this site, which eventually usually will lead them right out of The Troof(™)!
The JW religion is hemorrhaging members thanks to the internet and the multitude of informative anti-JW websites. (And perhaps it's even unfair to label them "anti-JW". I think they are more "PRO-TRUTH" than anti-anything.)
Once a doubting JW beings to see TTATT, well............it's all over!
The Borg is ramping up its emphasis on shunning as it tries to stop the hemorrhaging of its members contributors.