I think you missed the point of what I was saying. I'm not trying to put down anyone who plays in solo/private, hell I do it sometimes when I just want to be alone (I'm typing this while docked in Mobius private group). What I'm saying is, community goals are about bringing the community together to achieve a goal. You can do that however you want, BUT you shouldn't be surprised when a group of players work together to be more effective in the goal, and bang it out quicker. We honestly thought this goal wouldn't get passed tier 3 when we started it, but that quickly changed.
This game has many risk vs reward situations, and CGs are definitely one of them. If you play with other players, sometimes you can increase your efficiency, but obviously playing in open has risks, so it's a risk vs reward situation. For me, since I can afford the occasional rebuy on my big ships (as obvious by me attacking the station just to give everyone a fireworks show when we finished dropping cargo), I play in open for CGs and often for trading, because I enjoy those interactions, but when a pirate kills me 3 times in a row on my trading route, and my combat escorts can't get into the same instance as me and the pirate (despite navlocking my beacon), I tuck my tail between my legs and run off to private/solo.
Do what's best for you, but don't be surprised/upset when a group of players work together towards a common goal and do better than you.