Apparently, I missed the fun of the MFD debate, but situations like these raise troubling questions. Many of the arguments to delete the page boiled down to, "Pages like these do not help in building the encyclopedia. Therefore, they must be deleted." Let's ponder on that line of thought for a second, and analyze it, to see how problematic it really is.
The first portion of the position indicates that Wikipedia is only an encyclopedia, and that ancillary activities such as signing autograph books is tantamount to wasting time. While Wikipedia is primarily an encyclopedia, any editor that stays on the site for a significant amount of time recognizes that it is simply impossible to run and maintain the encyclopedia without any socialization with others. One of the site's raisons d'être is that whatever mistake a user does, a second user will correct; in order to maximize the efficiency of this self-corrective process, it is necessary to allow users some (note: not complete) leeway to socialize with other users.
Other users indicated that while they saw no harm in the pages, they also saw no use, so they should be deleted. While the "no use" is a personal judgment that I respect, I have to disagree with the "no harm" assertion. If a group of productive users is doing something such as maintaining a page to keep an autograph book, or an "office bracketology pool", or something that is otherwise innocuous, I don't see how it is productive to go ahead and say, "No, you are violating policy." The reason? There are two possible outcomes to this. The user stops participating in the side activity, but is also forced to go elsewhere, which means that he will spend less time editing Wikipedia. (Remember, the assumption here is that we're talking about productive users, not users whose entire purpose here is to use Wikipedia as a chatroom.) The other outcome is that the user resists and turns on the defensive, which increases the probability of occurrence of a heated situation.
Finally, it is inherent in human nature to try to personalize one's space, to make it one's own, and to make it a place where one can feel comfortable. From my own personal experience, I remember that back when I was a n00b, the first thing I did was to make a user page, so I would not feel as much of an outsider in a new place. Some users have previously indicated that they do not understand why this is an issue at all; however, for me, it was similar to extending one's arm for a handshake upon entering a new space. If I had had my user page prodded in the month between I made my first edit to my user page and when I made my first edit to Dubya, I would have considered Wikipedia to be a hostile place, and would have never returned. The last thing we want to do as Wikipedians is to make Wikipedia appear as a contentious environment.
Our success depends on how many editors are comfortable editing here, and taking actions that are "anti-User" or "anti-Community" on the surface do not help us retain badly-needed users. Our success depends on whether we can produce a culture that nurtures collaborative processes between editors, perhaps even more than on the quality of our articles. As a result, if I had seen the debate while it was open, I would have opposed the nomination, and !voted keep.