Very nice topic and I wish to write my experience too on this topic.
I used to vote myself and I stopped doing that. As such the blockchain does not restrict self voting but it is just a conscious decision that everyone takes. I personally don't see that as a big crime. There are bigger exploits we have on Hive.
One reason I was doing it was because I thought my content deserved more. But on the other hand curating will give us 50% back, so it is more healthier to upvote on others content in the end.