Allow reviwers to vote thumbs up AND thumbs down.
Allowing thumbs down would enable people to add narrative as to why something might not work.
e.g., Recycling. If there is no market demand for plastics, paying someone to pick up and/or store plastic (with $0 market value due to high transportation costs to foreign countries), then recycling plastic has no purpose.
On the other hand, creating a market in the U.S for plastics (maybe an idea for the Bureau of Prisons) would be a great reason for U.S. citizens to recycle plastic.