I just noticed that org-backward-paragraph raises a user error if you call it at the beginning of the buffer. This is not what the general backward-paragraph command does, nor is it what I remember other Emacs movement commands doing when the move can't actually be done.

I think consistency with other movement commands is reason enough to change the behavior of org-backward-paragraph, but here's a potentially more convincing reason: the function org-inside-LaTeX-fragment-p is supposed to return nil if point is inside a LaTeX fragment (and a truthy value otherwise). But since org-inside-LaTeX-fragment-p uses org-backward-paragraph internally, what actually happens is that it works as described *unless* you are at the beginning of the buffer in which case it doesn't return any value at all but instead signals a user-error!