It's less a reading of "GP endorses it as a route to making all your worries go away" and more one of "GP thinks it should be especially salient to us as a route to making all your worries go away". This is where I disagree. If the thought of erasing all your worries from the mind is tempting to you to the point that you "understand" the addictive potential of a narcotic drug through that one lens, your first-line approach should be learning about equanimity and structured therapy, not strong narcotics.

Also, clearly we don't need to "match the physiological response a brain has to fentanyl" (though there are newer substances like suboxone, now approved for medical use in the US and the EU, that seem to have some limited potential wrt. this), we only have to offer genuinely viable and sustainable approaches (which of course fentanyl isn't) to the narrower issue of dealing with the stressful worries in one's life.