The Stack Overflow Microsoft app contests rewarded people for asking legitimate Stack Overflow questions. In fact some of the contest prizes were hard to obtain

The Stack Overflow Microsoft app contests rewarded people for asking legitimate Stack Overflow questions. In fact some of the contest prizes were hard to obtain because they required X questions/answers with a score X or more votes. Many of the topics were sufficiently covered already, making additional questions/answers duplicative. However, this ensured that the integrity of Stack Overflow was maintained even if it did make the contest more difficult.