We might think about distinguishing between upvoting own blog posts and upvoting own comments. Upvoting own comments leads to excessive pointless comments only to be upvoted by the poster himself. The person who is upvoting all own comments does not contribute to STEEM anymore, as there is no free voting power anymore to upvote posts and comments of other Steemians.
We saw that after HF19 in the increase in comments and voting for comments. That was probably mainly people who created comments so they could upvote themselves. To some extent I did that as well short after HF19, the payout was just too tempting. I think it should be a valid proposal to think about disabling upvoting for own comments. This will again increase the free voting power all these people have and they will more vote for others again.
Upvoting own blog posts however, I think that is totally legit. You put a lot of effort in those, so at least you should have 1 vote, even if it's juts your own :D