The point more broadly is that if our society is willing to accept alcohol as a recreational substance with downsides, and more generally the idea that consuming recreational substances shouldn't be a criminal act, it makes no sense to send people to prison for consuming a substance that seems far less harmful in general.
> ...while a ban is not realistic due to its established role in society. This doesn't imply cannabis should have been legalized.
I disagree. Prior to legalization, cannabis already had an established role in society and saw widespread use. The primary difference between it and alcohol is that we sent people to prison for one, and didn't for the other, while also accepting the statistical reality that alcohol seems generally far more harmful. More harmful in terms of individual health outcomes and the downsides of becoming an addicted user, and more harmful to others around those who use it, e.g. deaths caused by drunk drivers, domestic abuse fueled by alcoholism, etc.
At least in the US (not sure about the climate in Germany), the reality was that cannabis use was already widespread, and that people's lives were routinely ruined for using it despite their use causing no harm to others. All while problematic use of alcohol routinely resulted in what are effectively slaps on the wrist, even when people routinely put other people at risk while driving under the influence.
It's against this backdrop that I'm comparing the two. Both were already pervasive. The difference in policy between the two made no sense.
And this is all before considering the clear upsides to cannabis. The medicinal applications are real, and have enabled people to live better lives without the downsides of the other widely prescribed pharmaceutical options.
Altering our mental states by consuming substances seems like a deeply human thing (in addition to be observed in other species), and is deeply embedded in us. I think there are very good reasons to ban some substances for the sake of public health. But I don't think a default stance against mind alteration is a good one either.