Most of the activity from 2012 in the stats is actually spam bots. It's why registrations were disabled for a year and a half until people decided to use this forum again, and why spam bot filtering was something I got sorted out early on this time.
Even though those accounts no longer exist, it looks like the "rebuild stats" feature in the admin panel doesn't do anything with them. As much as it'd be cool to not include that activity, it's also probably not going to be too easy to do, and it's not all that important anyway.