you make it sound like the swoopo of design!
The majority of effort (cost) expended is provided by the crowd - one person (the contest holder) gets to monopolise on this spread cost, while the majority of the people who take part in the competition end up with no payment or benefit whatsoever.
It's an inconvenient truth - one which many people who use 99designs try to overlook.
You're competing for payment. There's a big difference.
I think expecting participants to be grateful for the opportunity to practice stretches credulity a little.