I’d also say, who is your audience? If it’s startup CEO types of dev/CTO types then potentially they could use a board with ideas on it to start from. If its end users to get their feedback I doubt any would bother going there… and who would add ideas? What’s their incentive to share their ideas?
I think the best advice if you have an idea is (1) build something that solves a problem you yourself have and (2) despite the fact that “build it and they will come” is wrong, you do need to build some very basic UI if you’re going to talk at all to end users for feedback.