I saw an this post. The author describes a problem but uses the tags to define the version of Ubuntu, to give extra information. He doesn't mention the version in his text. I know that tags should be used to categorize posts. But can tags also be used this way?
Tags really shouldn't be used this way unless they properly categorize a post. Most version tags are plain superfluous and not needed (as in reality it affects more versions than that one). If you're already going to edit the post then remove that tag and add the information in to the text of the body.
The purpose of tags is to categorize and characterize posts. They are not a substitute for having information in the body of a post. That is, they do not substitute for saying what you need to say.
Both a title and tags are important and should be made so that when someone first reads the body of the post, they have some idea of what it is going to be about. But all the information in a post should be contained in its body (even if already contained in its title or tags).