Go-to-market is the whole system, not a department. It answers four questions in order: who is the customer (the ICP and the persona), what do we say to them (positioning and the value proposition), how do we reach them (the motion and the channels), and who runs it (the roles). Get the first two wrong and no amount of outbound fixes it.
The club exists because most early teams start at question three. They pick a channel, buy a tool, and only find out after a quarter that the list was the problem.