On snapzu the downvotes are not for disagreeing but more a moderation tool see here in one of my previous Posts. Specifically this by /u/drunkenninja

If we can all agree that the down vote button is a "moderation tool" instead of a "I don't agree with your opinion tool" we will all be better off and it will promote a far better community experience where unpopular opinions are discussed and hashed out instead of downvoted into oblivion. It would make general interaction so much more interesting.