This project might be harmful because of overjustification effect. [1] If there was some site 15 years ago that offered payment for writing an article on a given subject, would the number of contributors to wikipedia and thus the number of articles drop? Also, it is unclear how to fit formalization of huge projects like classification of simple groups or IUTech in "reward for a proof" approach. [1] https://en.wikiped…
There is a similar site [1] without external incentives (actually Proof Market is based on this). This site has active audience posting problems and proofs. Possibly Proof Market ends up in another example of overjustification.