I’ve certainly have been this guy. I’ve posted an idea that would be considered redundant, or “tinder for X” type of ideas. I think some sort of measurement next to each idea when being created can tell ther person how many time it’s already been mentioned.
Some other system to determine quality of the idea by creating a variety of sections. Depending on how much they fill out, can determine quality or perhaps some measurement of sorts. Spelling and grammar measurements as well.