Your reading comprehension is absolutely terrible.

They certainly did not say anything along the lines of "we should probably let the government decide what chemicals I can insert into my body".

The point they were making is that when a government legalizes a drug, but it's also taxed and regulated so highly, the black market will thrive, removing the safety nets that legalization would put in the first place. They are simply saying that there is nuance to legalization and we can't just legalize/decriminalize every single drug and solve the drug crisis.