They should have special rules on Patreon just for eroge developers:
1)All games must have an initial outline, scope for the story, gameplay description, approximate length....etc.
2)Games should have a reasonable time limit imposed on development time: 5 years to make a simple eroge is too much if you are charging people for it all the while.
3)Strict enforcement of deadlines/milestones within a realistic timeframe.
4)Supporters that have a cumulative amount of support for the devs above a certain threshold(varies per game) should be given the game for free.