I've never understood this line of reasoning. Every single one of us on this forum CHANGED OUR MINDS because we were confronted with some evidence that we just couldn't rationalize anymore. And the more we sought answers from the WT the more we realized what a house of cards their theology is.
No, you can't deconvert a JW in a single conversation. But it doesn't always take massive earthquakes to start an avalanche. Often it's a single snow flake that gets the ball rolling. And sometimes even one small point can have a profound impact upon the mind.
I should also point out that people don't change their minds because they "want to". Rather, people change their minds because they have no choice but to. Who knows what sorts of doubts and logical inconsistencies a JW may be noticing. Taking a moment to point out a few more is hardly a waste of time.
Using inclusive language can be hugely beneficial. Saying things like "how can we know that?" - "I understand that's what you believe but how can we tell if it's actually true?" - "do you think that we should have good reasons for believing the things we believe?" - can force them to think instead of just having emotional reactions.
All in all, I believe that people should have good reasons for believing the things they believe. And it therefore follows that if I want to change other people's minds (JWs included) I have an obligation to give them good reasons for doing so.
Simply saying "they'll never change their minds therefore I won't even try" isn't only wrong - it's also intellectually lazy.