Many people have argued for a long time for the complete decriminalization of all drugs. And there are many valid reasons to advocate for such a world. Not the least of which is that a country that fancies itself the "land of the free" but harshly polices and punishes people for executing their right to bodily autonomy in ways that don't directly impact others, is immensely hypocritical and damaging to the fantasy of individual freedom that largely animates this society.
The "criminalize drugs" meme is losing ground not because we're falling down a slippery slope, but because the bodily autonomy and individual freedom meme is proving to be more powerful and taking ground by force.
It's not a slippery slope.
It's a memetic war, and the stronger meme is gaining ground step by step through constant, brutal battles.
Drugs have been used as tool by the elites to control the masses for years, since at least the opium wars. Whereas religion was once the opium of the people, now opium will be the opium of the people, as Huxley intended.
Powerful people will always use whatever tools are available to control and manipulate the masses, including drugs, religion, media, and outright violence when necessary.
Another thing powerful people use to control the masses is criminal law. Criminal drug laws have now been used by the rich and powerful for almost a century to stomp on the face of marginalized groups and societies while giving their own foul and weak progeny and local society a pass.
This is what's coming to an end, and you are not on the side that history will look kindly on if you resist this change.
However, if you've done your own moral math and determined criminalizing drugs to be a net moral good, then please continue the fight, because we all must fight for what we think is right, even in the face of seemingly inevitable defeat.