The identification system (allows you to access your account from any device; which wasnt possible on the old account system) was implemented late 2011/early 2012.
For a period of time, it was possible to log on to your old account as long as you still owned the device the account was on and never deleted the app (I doubt that is possible now).
It is also no longer possible to manually transfer accounts and retain stats/items. And trying to recover an account this old by using the support site is probably a crapshoot.