I remember when I first began to frequent Meta there were jokes galore. And the moderators seemed pretty lax with humorous questions (and sometimes answers).
Then, something changed and Jeff began to lock and delete joke questions, and even joke tags.
Why exactly did such a change occur? Is it because at the time the change occurred, Area51 was just starting up and they needed to create a more serious environment for area51 questions? Or is it just that Jeff is becoming a grumpy old man? Or maybe Stack Overflow itself is becoming more mature and serious?