You actually have a great point here, thanks for taking the time to write it.
I didn't actually realize but my project with @treeplanter would exactly allow for self votes, as it's kind of like @randowhale
Thanks to your insight here (and not thanks to my own blindness!) I discussed it with the person in charge of it and we decided to add a note to the automatic comment to encourage people not to use it to self vote themselves. In time we might disallow it entirely but for the moment we will allow users to decide, as it is in steemit now, and see what happens.
You can read the statement here.