I don't buy it. I heard exactly this being said about cocaine, heroin, methamphetamine, ecstasy, and yes marijuana in the 80s. Reefer Madness was not a parody movie, and let's not forget that pot is still officially Schedule I in the US.
I'm not saying that all drugs require equal amounts of care - carfentanyl sounds more like a chemical weapon, and for that reason alone should be heavily regulated. But folks tend to overreact with panic every single time a new drug comes up, and I've watched this excuse ("no longer able to make free choices!") used to justify ratcheting up the drug war every time.
This particular claim doesn't pass the obvious sniff test - if fentanyl was so compulsive, heroin addicts would be seeking it out instead of trying to avoid it. Yeah, these powerful new drugs are killing people - and we should lay the blame square where it belongs, with the prohibition of milder alternatives.
I agree that users should be receiving treatment. But anyone selling or importing these drugs absolutely deserves to be punished harshly -- they are destroying millions of lives.