The negative incentive had been detailed before by @owocki here. Specifically, I want to avert the following scenario: “Person X contributes to get formal compensation (tokens, access to service, etc.) from the project”.
This is considered bad behavior (likely because that person’s contribution will be expensive and would probably be of lower-quality than contributions based on more altruistic motivations). There’s a lot of commentary about trying to discourage this behavior. However, the commentary in question (changing the code of conduct, internet memes, etc.) only regulates the discourse - what is said publicly. It doesn’t actually stop the incentivizing behavior itself. If someone is motivated to contribute in return for compensation, they will do so whether they post in a Discord channel or not.
As long as said formal compensation is still theoretically possible, there will be an incentive for people to contribute simply to receive compensation in the future, even if it is unclear when or if it will come. It may even lead into certain people who desire compensation instinctively backing any proposal that promises them compensation, regardless of its merits.
Only a limitation on compensation itself could address the underlying issue. If it is made clear that no compensation is possible, then this bad behavior will not exist. At this point though, I don’t know how one would be able to make that guarantee.
When you talk about rewards/airdrops, are you imagining a specific token or entity?
When I first posted this thread, I was thinking about Gitcoin Governance giving out GTC to certain parties as a reward for their previous contributions. This could have been generalized to any organization giving out any sort of reward to people based on what they did in the past.