I just started reading the Ubuntu Architecture wiki which outlines the overall architecture of Ubuntu. Got to the section that discusses the Ubuntu Policy Manual and that it is derived from the Debian Policy Manual.
I noticed that at the bottom of the Ubuntu Policy Manual that the document has not been changed since 2009-06-19. I also noticed the Debian Policy Manual was last updated on 2011-04-07.
Could be that no changes were necessary, but given the tight symbiosis between Ubuntu and Debian I would expect a more recent change date for the Ubuntu Policy Manual.
It could be that there just was no reason to update the document in over two years, but I am looking to better understand why?
When I go to the page in your link I see this at the bottom of the page
So, the answer is - not so out of date as it used to be.