I don't know if I see anything wrong with it unless you here a bad reputation from the people posting .. or its odvious this is a profit venture.
I think we need to look at them on a perpost basis.
If it becomes a problem , it might be worth while to put of a notifier than volenteer posts must be cleared first with an admin or moderator.
All in all, clear non=profit ventures seem fine, projects that have any question to them should go unless the user can explain the intent.
Honestly, the only way I got any "real" work for my reel starting out was via volenteer projects with independant film guys. And i know that more than a few kids got their foot in the door with that Major Damage volenteer project. or however that worked. SO I am postive towards them , but not to the point of taking advantage of anyone.