Well, I've just done this out of curiosity, but since a user is not allowed to upvote/downvote his questions/answers, is there any specific reason behind allowing him to vote for close his own question?
Why not? If the user has realized that it is a dupe or off topic, helping to close it seems like a sensible thing. I've done this plenty of times, generally with dupes.
- Centralised location to view closevotes
- "1 more comment" when you submit a comment
- Public beta--smoothly transition the privilege rep-requirements?
- Supercollider realtime updates incomplete-ish
- User A posted a question
- He got a good answer.
- User A finds another question which this one is a duplicate of also has an answer which does accomplishes the task in another way.
- He know both answers are good and useful to community, but there is a chance that only one will be searched and found by other people (since many of them stop searching when they get the answer). So he wanted to put those answers into one place.
- He can vote to close, saying this question is a duplicate.
Good samaritan. Ok, comparing this with upvoting/downvoting his own questions/answers.
- upvoting: No way it helps the community, if people starts to prop up himself to get attention
- downvoting: If he is good enough to know that his post is not wanted here, he shouldn't have posted it.
That is my take... There might be many other reasons.