Hello! Its really just a philosophical stance, since self-voting doesn't give any real information to the coming to agreement on quality, I really don't think it should be allowed.
But it is! And since it is, it can be done, and probably no one should complain about it. But I masterbate in private. Usually.
Upvoting is tied to reward. The problem is that reward is heavily tied to influence and visibility. Loosening the relation between reward and visibilty easily solves this problem.