I'm a bit new as well, about 2 weeks. I don't normally upvote my own posts, but I certainly don't fault anyone who does. Why not? I don't think there is any harm. I think I just feel I'm too new for it to make a difference. I have had a fair amount of success just interacting with folks here, though. It is a very active and welcoming community.
I'm not sure it makes a difference either @candidfolly but then I'm not likely to ever know. It's not like it takes any more time than upvoting others. I expect when I downvote someone...when it happens it'll be as easy to do as to upvote another. Likely I'd flag the post as well...it would have to be that egregious. Thanks for sharing your point of view. Best of luck to you.