This has been my experience as well.
Some people are more prone to "peak experiences" or "Shulgin ++++" or whatever you want to call these transcendental experiences. I have tripped countless (over 100) times and only had a fun, colorful time with no deep insights on the majority of those trips.
Then one day, I had a life changing experience in only 10 minutes while smoking DMT. I'm not going to get into a long trip report, but I had long and lasting life changes from this experience. My fear of death is no more. I went from a materialist atheist with a degree in the sciences to realizing my true nature.
I stopped bad habits. I started yoga and meditation. I study various Eastern spiritual material. My entire life changed, and for the better. That DMT trip was one of the most single important and defining events of my life, I'm still a scientist, but I am certainly no longer a materialist
I'm babbling, but the point I want to make is that I was an *extremely* experienced psychonaut who had sampled dozens of psychedelics over the past 10 years and I have only had a truly profoud and life changing experience one single time. If I hadn't had this experience, I would likely believe psychs had certain medical uses, but I would likely argue cockily and wrongly that they were not capable of anything *truly* profound.
Not everyone who trips will have a mystical experience, and some people have these experiences without ingesting any substances at all. These "peak experiences" are universal and need not be brought on by psychdelics, although that certainly seems to be the quickest way. Until you experience it there is no way to talk about it. Truly ineffable.