Did you read the article? As it says, there are multiple varieties of contest regulated by law, with games of chance being only one of them, and sweepstakes being only one of those. Your Wikipedia article is quite explicit about sweepstakes not involving skill, with reason.

The article agrees with you that design contests are not sweepstakes -- they are another type of contest which is subject to different laws. And while the article's truth would benefit its author, that does not mean it is untrue.