My two cents, I think they should be posted; and, if someone doesn't want to enter them, then they shouldn't enter them.
I find a lot of other sweepstakes being posted as questionable and useless to me, and I simply skip them.
For example, there are a bunch of travel agent sweepstakes being listed to win a $250.00 travel voucher. I won one of those and it was useless to me, because all of the agent's packages offered were all over $1,000.00 and the expiration date was only two or three months after I won it. It was useless to me. It was basically a coupon, and I wasn't getting anything completely for free.
I now simply skip all of those sweepstakes!
It should also be understood that when a sponsor opens the sweepstakes to countries other than just the United States, you aren't going to see as many winners posting. Especially, when most people don't post their wins; but someone is winning.