Marijuana and smoke are not tied together. Many people bake brownies. Some people smoke alone, so no others are affected. Vaporizers eliminate the smoke altogether.
It's not antisocial. In fact, it's one of the most social activities humanity has ever come across.
Police use the word antisocial here to when referring to it. I think they are using it in a completely different context though to how we normally use to word though.
More to do with out of line with how wider society expects people to behave or something similar.
In terms of the way we mostly use the word, yes it is a very social thing in bringing people together and having them interact.
It's not antisocial. In fact, it's one of the most social activities humanity has ever come across.