That's what research is starting to suggest for at least some opiate addicts.

Opiates have a very strong anti-depressant effect, that also tends to make the depression worse after coming down. Well, really it's the activation of "opioid" receptors (becoming a bit of misnomer) that have a very strong anti-depressant effect, which is the same mechanism that the anti-depressant effects of ketamine derive from despite not being an opioid (anti-depressant effect is almost entirely negated if taken with naloxone, aka NARCAN, to inhibit the opioid receptors).

This worsening of depression symptoms after coming down from opiates causes a vicious, psychological feedback loop in addition to the physical dependency. This also may be why ketamine has higher risk of addiction than other psychedelics like psilocybin.

Dissociatives seem to be in their own class when it comes to addiction, and I wouldn't compare them with your classic psychedelics that work at 5HT2A on that metric. A lot of people get addicted to dissociatives like DXM where you don't that kind of dependence and abuse with most 5HT2A agonists.

Many dissociatives also inhibit dopamine and norepinephrine transport, or induce their release, which can have rewarding and addictive results on their own.

I agree, it wasn't a great comparison. I didn't want to get too into the weeds on specifics since I figured the average person would lump them all under "psychedelics" or "hallucinogens". I just wanted to point out that the activation of opioid systems may be a contributor in its more addictive nature, but it's certainly not the only factor in its addictive potential. Especially so since those dissociatives that activate dopamine or opioid systems tends to be more addictive than their more selective counterparts.