I am not able to upvote or downvote my own post. And it's fact.
This question Why can I vote to close my own question? gives some idea regarding closing question. If I post a dupe on accident, and someone points it out, and realize my mistake, I can help correct mistake by voting to close my question.
Somewhat true. But what's the benefit for keeping ability to reopen my own question.
Why I am able to open and close my own question?