Of course opioids play with your brain. So do SSRI antidepressants for example, whose very name is based on their most commonly accepted mechanism of action. And it's not only strictly psychiatric drugs—ADHD medication also plays with your brain, influencing dopamine pathways. But then so do gambling, and physical exercise, and meditation! Heck, even social media plays with your brain.
The mere fact that something has an effect on the brain is not in itself an argument against it—let alone when it is being proposed as a psychotherapeutic tool.
You're comparing something that happens to anyone taking opioids long enough, to the worst thing that you can imagine to happen on shrooms, something that actually happens to ~nobody who has taken shrooms, and somehow trying to table that as an argument.
Meanwhile, I can walk through tent cities in Vancouver of people getting free opioid injections from the government because they've given up so hard on this ez addiction problem. And I'm supposed to somehow see how shrooms are actually worse.
You said you're playing devil's advocate, but you still have to try to make an argument. It just sounds like you're field-testing a half-baked supposition you came up with 30 seconds ago.
Opiate harm is also not limited to addiction. Overdosing and liver toxicity from (abuse of) prescribed opiates is real and driven by their steep curve of tolerance. Opiate withdrawal for many can be harsh enough that it's worse than the pain being managed, leading to perverse outcomes like theft, violence, exploitation, and addictive cycles. Inhibitions are also altered under the influence and during withdrawal leading to riskier behaviors and accidents.
Those are the low-hanging rebuttals. We already know the societal cost of opiates far, far outweighs the damage of other recreational substances because of its availability, potential for harm, effects on interpersonal relationships and mental state, and propensity for addictive abuse. Psylocybin has mild potential for mental addiction but none of the cofactors for abuse or deleterious side effects on health.
It was unpleasant but I ultimately came out better than I went in. Maybe it doesn't work for you, but rebuilding worked for me and made me stronger.
Source needed. All the research I've seen suggest that psychedelics, nay many serotonergics, boost BDNF and neurogenesis.
However, they may artificially weaken links to fear circuitry in the brain - this is usually a feature.
Other than that, I think you are absolutely right tho, mushrooms can induce severe changes. I am not for legalization. And I believe your point is why most people under legal psychedelic treatment are terminal patients.
Shrooms play with your brain. We barely know how that works and quite frankly a lot of the research into managing the depressive episodes with shrooms may just be that you become more stupid and therefore less prone to thinking in the first place.