Wise words there. I would love to work in a proper team, but I have never really had the pleasure. What I've noticed is, the people with all the skill and experience (a) have no time, and (b) what little time they have, they want to spend it on their own projects. This means you end up with a lot of less experienced people trying to make teams without the hardcore veterans there to hold it all together!
There has to be one key player, in my opinion. One core coder with the vision and the skill to do most of the legwork. Most of the older players here have had to become competent in all areas (coding, 3D modelling, texturing, 2D art and sound), in order to get projects finished. You need to have someone like that at the core.
After that, unless the other team members are getting paid, they really need to share the same vision. If someone asked me to help with a game, it'd HAVE to be a post-apocalyptic zombie survival game. Why? Because it's the only game I haven't made that I've always wanted to make. It's my dream game. It's the only way I could be counted on to stick with a project.
If your freebie team mates aren't long-term passionate about the core game concept, they will, with 100% certainty, do you over at some point and not deliver (unless it's a quick project).
...... so while we're on the subject, whose 1 single long term core dream, before they die, forsaking all others, including their wife and own bodily urges and desires, wants to make a realistic zombie survival game? Speak now, if you exist.

<-- Cheeky smiley, but I ain't joking!