I mostly agree with you. I feel many motivational books are very superficial and they're no substitute for experience. Most of them make me want to vomit - they're so saccarine sweet.
However what you call "exploiting someone's vulnerability" might be hand-holding and supportive for someone else. When someone's in a difficult & stressful situation, they may not see the straight-forward practical advice that you would be aware of.
Have you considered a career as a self-help author? Maybe with the straight-shooting gonzo style that you have here. It would be a great difference.