It was one guy, but quite persistent. Unfortunately, he used a strategy the existing moderating tools were not good for. (The tools are focused on moderating content, not vote manipulation and sockpuppet creation.) And the Reddit codebase (which LW uses) is very difficult to work with; even very simple ideas for new moderating tools took forever to develop. In long term it will be easier to switch to a completely new code, which is what LW 2.0 is (also) about.
It was one guy, but quite persistent. Unfortunately, he used a strategy the existing moderating tools were not good for. (The tools are focused on moderating content, not vote manipulation and sockpuppet creation.) And the Reddit codebase (which LW uses) is very difficult to work with; even very simple ideas for new moderating tools took forever to develop. In long term it will be easier to switch to a completely new code, which is what LW 2.0 is (also) about.