Come to think of it... does the forum here ever do group or themed builds? I remember decades ago the old WWI Modeling Page used to have the occasional 'cook up'. I never participated because I'm too slow to finish anything, but I love the idea.
We have done group builds here in the past, which included judging and prizes. This was before my time as a moderator, but I believe that there was a mixed response from the audience; some folks wouldn't participate unless there were prizes. Some folks complained about the prizes on offer ("wrong scale, not something i'd be interested in, surely we should get something better", etc). Some folks were not interested in participating unless there was something in it for them, rather than looking to the overall character and spirt of the forum. The administration (organising prizes, sending them out, etc) was too costly and difficult due to the fact that we rely on donations for things like postage (noting that they needed to be sent from Australia, and postage is certainly not cheap). IIRC there were also some prizes that got lost in the postal system. I believe that poor Dave copped quite a bit of grief right the way through the whole process.
I think some of this is the reason why we haven't gone down the path of group builds for some time (not to say that we can't or won't in future, but I think it would need to be carefully considered).
Cheers,
BC