Nice piece. I wish I had some answers for you. I've been thinking about this a bit. Personally I think self-voting is OK on posts where authors need some exposure. Most authors would struggle to write 2 decent posts a day so that still leaves 8 x 100% votes that need to go elsewhere.
Self-voting comments I consider OK only as means for curating the comments. Frequently these can be much lower % votes if you're just trying to bump your comment (usually an answer to another comment or question)
Clever abusers then create multiple accounts and "circle jerk" to hide their self-voting. Harder to detect but not impossible. It is generally easier to spot the "good actors" from the "bad actors" so I personally think there should be focus on rewarding the good rather than punishing the bad.
I'm in agreement there. Promoting good actors is happening at some level already with various community projects forming. The bad actor... Well, at least some we're quite good at spotting. The only thing I'll point out is that going after blatant bad actors that take a huge chunk of the reward pool gives the greatest return on effort in terms of improving it for everyone else.