I don't know I think downvoting is necessary to flat what needs to be flagged, copyright infringement, hate speech, stalking and such, but it's been misused and though I do not believe in censorship maybe perse I believe in community consensus that community should be able to point downvotes as non legit and maybe nulify them... I don't know. I've been sometimes in the middle of wars that I've not been even aware of, like I come here and post (I am a slow creaaaaator, sloowwwww but steady) and at least when on "steemit" I was caught in the middle of a few with a big discouraging downvote out of nowhere simply because another had voted for me or reposted.
I think free of speech also has a limit (sorry, unpopular opinion I guess) when it's HARMFUL or DECEIVING or with the intention to scam, harass, etc. Let it be used for what it should be used, maybe there should be a FIELD on downvotes to VALIDATE the reason TO DOWNVOTE, like picking (copyright theft, harassment, etc) and it would force you to pick a field to cast it