Personally, I feel that review campaign brings more results to the project owners because the participants of the review campaign will surely use the project and there is the possibility than more than 30% of the campaign participants will continue to use the project if it is a good project.
I respect your opinion, but it made me wonder what makes you so sure that participants in the review campaign will continue to use the service after the campaign ends. There is no confirmation of this, and it is not possible to obtain any kind of statistics to prove it.
Then this can apply to casino projects, but how can it be applied to mixer projects? Those who try Mixer as part of the review campaign cannot guarantee that they will be regular users of this type of service.
There is a difference between a signature campaign and a review campaign, and each of them has its own goals, which Royse777 summarized in his comment above.