There could be another possibility. I think each case officer has to review specific numbers of application per day and provide AOR. It is possible that they put difficult applications aside and review easyone, those who have not exit Canada during the last five years or those who lives in same address.
i highly disagree you thought but good points u mentioned.
i have applied 11 OCT 2017.
you can say I am easy case: YET no AOR.
1. have never travelled outside Canada since day 1 arived 2010, long before eligillity
2.Lived only 2 addresses same town since 2010 current one is since 2012 since eligillity.
3.No employment since severe injury 2013 but that doesnt determine eligibillity.
4.sent Drivers License, PR Card both sides copies, COPR, Language certificate, protected person Doc status copy as IDs every id and explained Y i dont have passport.
5.Applied as single so no baggage.
but still no AOR, so i think they first open Courrier mails for Dartmouth address, majority of also who got AOR are from Calgary & Vancouver so CIC might hate Ontario & Quebec applicants.
according to Google spreedsheet and forum replies on this site its proof they CIC like people who applied from calgary and vancouver and want them to feel welcomed for quick intergration.