I like the original premise for the upvote, which was that you don’t vote on whether you agree but on whether the comment/post is a good contribution to the discussion. The upvote should be a way of saying “good point (even if I disagree)” and the downvote should be saying “this is irrelevant or otherwise doesn’t contribute to the conversation.”

Of course, almost nobody uses the vote this way anymore. While your granular voting is quite interesting in principle, in practicality it seems it would negatively compound the existing problems with the vote system, namely that instead of voting to support the continuation of good faith discussion, everyone is voting to support just their own ideas. That in turn leads to fractious discussion (if we can even call it discussion) where the most popular and well-known ideas are strongly upvoted and continue to circulate, and anything deviating is barely seen. Then you don’t really have a discussion; you just have a series of highly upvoted statements. (See, for example, Reddit.)