Much of the benefit of psychedelics is the introspection, which you can do sober as well (although the depth of the reflection is magnified and qualitatively different while tripping).
This is confirmed by the linked study (which shows that placebo-ketamine is also very effective).
Many psychedelic-era personas expressed this sentiment as well: you don't need psychedelic drugs to reach that state, you could also spend 10 years practicing meditation daily.
This view ignores the major application of these substances. Ketamine-induced self-therapy is accessible instantly and acts as a major reset. When you are experiencing long-term depression and/or anxiety, the advice to "just meditate" or do deep introspection is wildly counter-productive. Depressive state is very frequently accompanied by an unhealthy focus on the internal voice and on over-analyzing own life/motivations/purpose/etc. Having an "introspection session" in this state is a borderline dangerous advice.
I just want to endorse this comment. Psychadelic drugs have a miraculous property: they elicit transcendent states reliably. Eat the mushroom and you will experience it.
There are corresponding risks to this, of course, but that's the flip side of their utility as a (sharp) tool.
these tools allow exploration of not just introspection but also states that otherwise belong safely behind a closed door.
Yes I might actually enjoy having countless shards of the universe's ideas slicing through my ego for a few hours at night over the weekend; no I never want that to experience that during a workday.
Working is overrated and may be part of the problem of having depression in the first place. Maybe we are solving the wrong problem after all. Depression is a signal, it’s evolution whispering that life sucks in some major way. Throwing SSRI at problem silences this voice. But maybe it does and psychodelics fix that, instead of suppressing alerts indefinitely.
Meditation is really about changing your life. It’s a daily practice like exercising. It’s taking action and doing the work. So it probably offers longer relief from depression since it is a life change.
There's also reliable studies that it isn't that, and I actually expect it isn't, since antidepressants in general don't work by making you introspect. Actually "rumination" is a symptom of depression, so they would make you do it less, and IME meditation is not about introspection either.
Here's one showing a mechanism ketamine and antidepressants both act on:
This is confirmed by the linked study (which shows that placebo-ketamine is also very effective).