For some reason it seems even scummier than rigging votes so maybe that discouraged it. But it's no surprise that admins would have a "work" account and an "anonymous" account. You'd never be able to express a personal controversial opinion without it being jumped all over and attributed to the company.

Somewhat related: Did you have to comb through all of your past comments before the interview and/or announcement? It must have been weird interviewing at a place where you'd had a personal account prior to being interviewed. I would have been filled with anxiety wondering what weird stuff (oh golly, and porn...) I'd looked at while logged in.