To expand on Mewiet's answer, I explained in Thread:177648 that it was decided years ago that cast/crew birth dates must be properly sourced. Yes, there are still lots of dates on this wiki that have unsourced dates, but another user and I have been working to remove those. Please read the forum thread that I mentioned here to see more information.
This might be a good chance to remind all users that one or more violations of a rule do not make the rule invalid. This is a large wiki, and sometimes mistakes slip through the cracks.