I've battled anxiety my whole life, and much of it a result of association and being brought up as a JW. Never had high wages because I pioneered instead of going to college despite numerous scholarship offers, so I struggled to make a decent wage. When I did make good money I had no clue how to handle it because money was always just a means to an end. No need to save any because this system will end soon. I struggle with social anxiety because I'm so different from others and was bullied so much growing up. Now that I'm fading I'm constantly thinking the car doors closing outside are elders coming to talk to me. Screwing up and getting disfellowshipped and losing all of my family was a constant fear, though I've pretty much lost them without even managing to get disfellowshipped due to the organization anyway. I've always been worried that I was going to be thrown in some sort of horrible camp where I would be tortured for my faith during a great tribulation that has been held over my head since I was a kid. And if, IF, I managed to do all of the right things there was a chance that I MAY be concealed in the day of Jehovah's anger and not be thrown into everlasting nothingness, but if I messed up it was all over, which I guess part of me feels now that I can't buy into what I was taught growing up anymore. Oh, there was always a fear that you'd listen to the wrong song and someone would rat you out, or say the wrong thing or talk to the wrong person. People are always watching us as JW's to catch us in a slip up whether inside or outside the organization. And I could have stumbled someone and been worthy of having a millstone tied around my neck and been hurled into the sea because I read a book that another brother or sister didn't approve of and they were so easily stumbled.
I could go on forever. As to what you saw, I don't think they're actively recruiting the mentally ill. For one, they don't have to, they flock to the organization and the congregations I was in were full of such illness, probably me included (though miraculously so much went away as I distanced myself). I'm sure that it was just a marketing message to attract people that face something so common today, that of anxiety, and to try and offer comfort from the scriptures. Of course, along with that comfort that they'll point to will come a whole slew of new things to be anxious about. Don't forget that the Devil is running about like a roaring lion, seeking to devour you at every turn. See, new anxiety for the uninitiated! You're welcome. :)
Just to be honest, I should probably add in that I come by anxiety naturally as well, and I'm an over-thinker. Look at my posts. This is probably one of the shorter ones, lol. My brain just goes and goes naturally.