I believe in spreading the upvotes around but also it is OK to upvote your own posts too.
So long as you are sharing your upvotes and not upvoting only for your own posts or comments...if you are doing that, then that is very bad manners on Steemit.
I see those who vote for their own posts and comments as no different really than those who automatically upvote certain members posts simply because they are in a certain 'trail' or 'community voting group', this is also depriving the other members of upvotes too....Is there really a difference between self voting and communal voting, both do take away some of the upvote pool.