Ugh - if that's the case this place is less open to discussion than I thought. I was honestly curious if it could be a possible application for a technology that people constantly complain has no use.
Oh well, keep em coming. The downvotes only make me stronger ;)
But what's the actual implementation? Just suggesting a hot topic might have applications without specificying how isn't really starting a discussion. As other have said watermarks deter unauthorized use, they're not a proof of ownership.
Don't take downvotes so personally, they're more about weeding out bad ideas from good ones than a reflection of your worth to the community, this isn't reddit where we care about karma count. If you fix up your comment instead of complaining you might see those downvotes get reversed (I've had that a number of times).
But if you're going to use blockchains for voting, you might as well use them for the whole thing. Every new comment, every edit, every deletion and vote. Consensus as moderation.
I didn't downvote you, but I suspect at this point people are a bit fed up of the constant suggestions of using the Blockchain for everything.