Marx certainly didn't invent socialism or 19th century socialism or even communism; he was a critical scientific examiner of capitalism and a communist, who was able to criticize other socialist positions for being weak and insufficient in actually changing capitalism, and then went beyond others before in specifics critiquing political economy.
There should be a labor or organizing comm, seriously. Tactics is kinda related and sometimes organizing and labor matters are posted there, but it seems like it would be suited to have its own portion.