alt Hacker NewsI maintain a niche-popular project that I didn't do any marketing for. My understanding is that even for popular projects, the usual dynamic is that there's just one guy doing all the work. So "getting off the ground" just means getting people to use it, and there shouldn't be any reason to artificially force that.
It depends what your objective is. Many people seem to see their open source projects as a stepping stone into some commercial activity. Putting aside whether that is a good idea or not if that is what they want to do then they will need to market in some way.