Why would you put 200 shares at $50 and 100 shares at $100 if you only had a $10,000 budget? That's misrepresenting your actual demand curve.

Are you saying that an auction of this kind is a bit complicated, and it's possible to make a mistake? I suppose that might be true, but that is a very different assertion from your original position:

"since people had to enter a single point on their demand curve as a price and quantity of shares (instead of their entire demand curve)"