Some of us have likely heard of David A Reed, a former JW elder and later Baptist Minister. He is also a rather prolific author of religious books, including one entitled "How to get Jehovahs Witnesses to Listen".
The following is an extract from a January 1990 interview with him by Investigator magazine, and specifically refers to the role protestors played in this couple (David and Penni Reed) waking up to the fraud that is the JW religion.
What broke the spell and enabled you to leave the organization?
DAVID: "Bible reading! The Scripture is true that says, 'the word of God is living and powerful, and sharper than any two-edged sword'." (Hebrews 4:12 New King James)
PENNI: "We were at a Witness convention, and. a handful of opposers were picketing outside. One of them carried a sign that said, 'READ THE BIBLE, NOT THE WATCHTOWER'. We had no sympathy for the picketers, but we did feel convicted by this sign, because we knew that we had been reading the Watchtower to the exclusion of reading the Bible."
(For those interested, a record of the full interview can be found at https://ed5015.tripod.com/jwelderdavidreed10)
From accounts such as this and others, it would surely be rather narrow minded to dismiss all anti-JW protests as ineffectual (or worse)?
(Yeah, all-right, I know this is "merely" anecdoatal evidence! However, even anecdotal evidence has to be taken into account).