Eliminating “abuse” is not possible and shouldn’t be the goal. Even those who are attempting to “abuse” the system are still doing work. Any compensation they get for their successful attempts at abuse or collusion is at least as valuable for the purpose of distributing the currency as the make-work system employed by traditional Bitcoin mining or the collusive mining done via mining pools. All that is necessary is to ensure that abuse isn’t so rampant that it undermines the incentive to do real work in support of the community and its currency.
The goal of building a community currency is to get more “crabs in the bucket”. Going to extreme measures to eliminate all abuse is like attempting to put a lid on the bucket to prevent a few crabs from escaping and comes at the expense of making it harder to add new crabs to the bucket. It is sufficient to make the walls slippery and give the other crabs sufficient power to prevent others from escaping.
Many, many people buy more Steem with cash every day (that is, they "climb into the bucket") not because this gives them more power to award other people Steem but because doing so gives them the ability to gain more exposure for their own posts (via self-voting). To deny everyone, even posters of quality content, the ability to self-vote because a few abuse the system is to "put a lid on the bucket". Yes, it prevents a few bad crabs from escaping, but it also prevents far, far more from wanting to enter (buy more Steem).
There are other less draconian ways of dealing with self-voting abuse, such as flagging: "It is sufficient to make the walls slippery and give the other crabs sufficient power to prevent others from escaping."
Quite simply, self-voting is not a rampant problem. Steem is doing better than ever--high price, more posts, more comments, more new users, etc. It's growing exponentially. As we say in the South, "don't try to fix something that ain't broke." We can't let our resentment for a few abusers cause us to make short-sighted decisions that undermine one of the key value propositions of Steem--that you can gain more exposure for your own content by purchasing more Steem and responsibly self-voting.