The problem with abusers is that they are more motivated to abuse than the whole community is motivated to fight them. Plus, there are few angels really. Everyone abuses the system, even slightly, sometimes. So, sometimes the demarcation line between a person who is generally ok, and maybe crosses the line a bit or sometimes because he or she sees this is a practice, and the "evil" abusers, is a little blurry.

Unfortunately, as you remarked, limiting the number of posts per day is not a solution that cannot be easily circumvented by a motivated abuser. It's the correct person who might cross the line occasionally who will get burned by this.

Same with self-votes. Unless there is one who self-vote everything he or she posts, including (or maybe especially) comments, this is something most people do (there are exceptions of course). The really abuse is not as easy to stop as to disallow self-votes. That would be simple. It now happens in the so-called circle-jerking understandings. And if those understandings won't work any more, they will morph into something else.

As long as there will be a reward with a monetary value attached to it, there will be people trying to abuse the system. The fight will be ongoing and no side will win definitely... ever. Unless we evolve as a race and/or monetary incentives lose their value over something else.