I don't know that everyone in dubland can be helped to see the light, but I know how I have helped some.
In a one-on-one situation, I have helped get some out. But that is not always possible.
What has otherwise proven effective is a carefully crafted letter sent to a dub in the mail.
As brought out in the OP with the article quoting Watchtower counsel, dubs don't read that stuff. Yep, I get that. After 50 years in the cult, I understand that.
.... unless you carefully craft it and send it to all their neighbors too. And when I say "carefully craft it" I mean construct it with their neighbors as the audience, and craft it so that when the dub opens it, they understand right off that this was sent to their whole neighborhood.
They'll read it.