Self voting keeps you from voting on other content, and that keeps you from generating relationships. Those that find their rewards are coming mostly from their self votes might note that their own votes are limited in number, but the votes of the community are limitless.
For folks that have a grip of SP, self voting is self defense. If your vote is worth $100's or $1000's then not self voting seems like wasting opportunity, and that makes poor business sense. However, you're then trapped by your SP, and unable to curate and grow Steemit in the direction you want it to go.
What really chaps my hide atm, is VP decay. I haven't voted in days, and my VP is barely above 50% last I checked. I consume a lot of content on Steemit, and want to upvote everything I like, even a little. This becomes hundreds of votes per day, and my VP will not recharge, meaning my vote becomes motivationally meaningless.
TBQH, that's a lot worse than self votes, even though self votes account for a far greater concentration mechanism for wealth. The network effect of getting many minnow votes is very motivational, even though ppl want the whale votes (of course. Who doesn't like money?).
Disempowering minnows from voting, as has been shown in my example, dramatically reduces curation, which is the lifesblood of Steemit.
RE: Why Minnows Don't Buy STEEM