No, I appreciate there's no real distinction between blogs and comments, in that both (or neither), can have value.
The trouble is, other votes fall into that category too, such as those from bots and trails. It's not 'subjective proof of value' if people are clicking because other people are (without viewing) is it?
It's not proof that the stakeholder views the specific post as valuable, but it could be indicative that someone finds it valuable. If a blogger has created 100 posts and every single one of them was good, or a voter has upvoted 100 posts and every one of them was good, it can be reasonably expected that their next vote/blog will be good as well. There are obvious flaws in this, but it can work to some degree. For some it is better to reinforce other subjective entities than to leave stake idle.
A self-voter who usually gets many 'organic' votes for their blogs, could then be forgiven for up-voting their post on this basis too I guess? I know what you mean, I end up under-voting.
Yes, I think so. If someone is getting lots of votes for their posts otherwise, that is a degree of social proof that their posts are valuable. I still think it is preferable to lean on others than yourself, because of self-serving biases, but I'm not going to go on a tirade against the people self voting who are providing clear value.