I suspect it's another way of ensuring the loyalty of the Jem'Hadar to the Founders. If your soldiers are addicted to a drug that can't be replicated and only you can provide, that gives you a great deal of control over them.
I never thought I would say this to you, Odo, but you are listening to your heart, not your head. That boy was created in a laboratory! His body, his mind, his instincts, are all designed to do one thing; to kill.
My body, mind, and instincts were designed to be a Founder. You were trained to be a terrorist. But each of us chose to be something different. I just want to give him the same chance we've had!