The OP of this question told me privately he couldn't up-vote my answer because he had insufficient points. The site wouldn't let him.
When would he?
At the Help Center > Privileges page it says, amongst many other things:
15 - vote up - Indicate when questions and answers are useful
1 - create posts - Ask a question or contribute an answer
Although not explicitly stated, my understanding is that as soon as you have the privilege to ask a Question, you also have the privilege to Accept an Answer to it.