We do send guys who sell crack to kids to prison though.
I don't care how "non-violent" they may be at that particular time, but drug-dealers aren't exactly known to be toothless softies. They are heavily armed with illegally obtained weapons.
I've never read of a major drug bust that didn't include: "Drugs, a large amount of cash and WEAPONS".
It makes for a handy argument (”if we’d only legalize drugs our prisons would be half as full”) but it makes as much sense as so many other arguments made in the political arena - pick your favorite one - you can raise revenue by raising taxes, if guns were illegal criminals would gladly give them up, welfare doesn’t create a dependency class, if we only gave up our weapons our enemies would give up theirs etc. etc.
All basically examples of sophomoric thinking.