Can we please let the community close questions?
I quit using Physics Forums because of a single case of moderation. I started a thread on the site to do a general relativity calculation in public. Along the way I was told by several respected posters that what I was doing was hopelessly wrong. Eventually a moderator closed it: Schwarzschild Orbits in Cartesian coordinates
The result of my calculation was a paper that was the first amateur paper to win an honorable mention in the annual gravitation essay contest: http://arxiv.org/abs/0907.0660
The basic problem with allowing single people to close posts is that single individuals (heck, even groups of them) do not know enough about physics to distinguish between crank efforts and real physics. Sorry, physics is big and each of you, individually, is quite small. If you allow individuals to close threads you will eventually have this sort of problem drive people away.
I'm reminded of a statement by Harry Collins (a sociologist specializing in physicists):
One of my failings ... is that I cannot generate the levels of disdain for physicists that one physicist can generate for another; I know what I am missing because ... in my own field I can readily generate such levels of disdain for some of my fellow social scientists!
The problem with disdain is that it is an emotion that can blind the reader. And the people most attracted to giving effort on Stack Exchange; do you think they're going to have LESS than the average level of disdain? I suggest that they're likely to be those who have more difficulty "getting along with others".
In short, the reason you should not have single moderators closing topics is the same reason physics journals use more than just a single person (the editor) when deciding whether a paper is worth publishing.