A business does not turn to their marketing department to determine what games to develop next. Sorry, it just doesn't work like that. Their R&D team is going to handle that.
You are mixing what a marketing department does in a specific company with the concept of marketing. I have a degree on this.
Besides, thats not what i said. I said both are possible. I assume that what you are talking about are companies with clear defined segments they work in. How else would R&D know what to work on? Make fridges or make match sticks? The definition of that segment is marketing on the strategic level. Your common marketing department works on it in a tactical level.