"While we've been advised to save down-votes for spam and abusive content"
To be honest I think this can only work with very-low value accounts. I hate to downvote spam because I'm wasting 2-3-5 cents that could be used to reward someone. If my account vote was worth like 0.0001$ that would be different than 0.02-0.05$. And if you are a whale, I guess a -500$ upvote for spam or not-critically-abusive stuff is not an option and you are kind of forced to leave it for other people.