It might be nice to have the concept of an alias account - an account type that functions normally as a user but in most respects refers to another account. Allow me to describe three use cases:
1. In a large open source project that I am a regular contributor to (not that it is going to be transitioning to Phabricator anytime soon - I made the mistake of championing a conversion from CVS to SVN back in 2006, and don't plan to take on another institutional change, as much as I'd like to), we have a role called the Build Czar (bczar). Nominally this person is responsible for monitoring daily builds, cutting releases, etc. The person holding this role might have elevated privileges; for example in the case of a fabricator based workflow: modify build plans in Harbormaster, edit Herald rules related to projects/repositories, be a gatekeeper to new commits/revisions during the run up to release, etc. Instead of remembering who is the current build czar, it might be nice to be able to just say `@bczar` in a task/revision/etc to refer to this person. Moreover, changing permissions when handing over the mantle to a new person would be greatly simplified by simply changing the user/users the alias pointed to.
2. On this Phabricator install, I have to accounts: @wotte and @wrotte. One was created unintentionally, both point to me, but emails go to two accounts. I'd like to be able to point @wrotte at @wotte.
3. This could be used as a vehicle for implementing T406.