FamilySearch Digital Collection Vanishes

I recently wrote about the Arizona, World War II Draft Registration Cards, 1940-1945 collection on FamilySearch.org where I found my father's draft registration card. See World War II Arizona Draft Registration Cards on FamilySearch.org.

I got a comment that the collection had disappeared and so it has. The link comes back with the following page.

I am disappointed that I relied on the link and did not immediately make a digital copy of the card. Now I do not have a copy of the card except on my blog's screenshot. How do we know why or how this happens? I saw that there were many of my uncles and other relatives represented in this collection, now I do not have access to add these sources to my portion of the Family Tree. I checked to see if the collection was on Ancestry.com but did not find it there either. Hmm. Does this mean that if we find a collection on FamilySearch.org we should immediately copy all the documents we can find to make sure we have a copy? Does this also mean that every document linked on FamilySearch.org should be copied and added to the Memories section?

I know some people have already been making copies to their computers or onto the Memories section of all the documents they find. I hope I do not have to start doing this.