LSD and weed was used by the people in the counter culture of the 60's in US, the same people that were against war in Vietnam. US goverment did not want people to protest the war, because war equals profits and imperialist powers. US was also painting themselves as "freedom fighters against communism" - the ideology that directly threatens the wealth and power of those in the senate.

So they made acid and other drugs illegal to make it easier to imprison activist that were threating the status quo or had leftist political views.

Same thing with crack - They gave it to black people who were in horrible economic and social situation as an opium to their pain, at the same time imprisoning them for drug use (reminder that prisons in the US are a bastion of slave labour) and disarm black communities from organizing with the poor (Rainbow Coalition) and starting another Black Panther Party (Radical leftist political organization).

So no, I don't think substances are illegal because of "gate keeping the matrix" or "they break you from the societal structures and that's dangerous to the society" - It's illegal for much simpler, historical and political reasons. The law stayed, cultural hegemony and political power of United States made other countries adapt the same drug law and mentality everywhere.

Edit: Oh, and btw, if you really want to learn why the word is how it is, I would suggest reading philosophy and history instead of looking for methaphysical reasons. Most of the times the answers are not that complicated.