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.