No one was protecting dopes from themselves with any laws. The laws are to protect the innocent. The innocent being the lucid guy going to work, pursuing happiness, education, lifting himself as best he can, and protecting his children from the sewage of the world.
The innocents are the children. They who are born knowing better than that dope(s) will do them any good. Unfortunately, those children are sometimes conceived by, and subjected to dopes as parents, which only begets further dopey behavior, attitudes, and of course, moral and criminal negligence, indolence, permissiveness towards other behaviors, and false complacenies about what is real, or how reality is dealt with, and what uplifts and is redeeming. Yep, dope is benign. Its use, proliferated further by having its immoral stigma reduced and eliminated, will make for a pretty dopey, benign society. And yet there will be more children. Children, for whom there is responsibilty, and consequences.
Where do you propose to draw the lines regarding what is moral, or if there should be any lines, at any point, over which mankind does not deign to do, falsely proclaiming it as "freedom?"