Something can be legal while not being socially acceptable, and we can still strictly police related harms. Like with drugs, we can legalize them while still making e.g. smelling up an area with marijuana carry a public nuisance fine, or make littering with needles a misdemeanor (or more severe if someone gets injured).

If someone's only crime is being disturbing, the government doesn't need to get involved, but we can still not want to be around them and especially keep kids away from them.