Exactly – I thought about the same exact thing plus more. Originally, this is what I kept thinking:
Adcom most likely wants to maximize efficiency in evaluating the 673 applicants.¹ As a result, when they categorize applicants into Above Average, Average, and Below Average interview scores, they may automatically reject those within the Below Average category. After all, the interview stage is all about the interview stage. So, if someone does poorly on it, there is no need to evaluate their file. As a result, only those within the Average and Above Average categories are eligible for a post-interview evaluation. To further maximize efficiency, they may also look at applications in order with Above Average applicants first. Since those with strong performances already did great on the interview, it makes sense to look at them first and quickly see if they meet other criteria + some extra evaluation, and then have some get accepted. Then, they heavily think about people within the Average category because (1) there may be many of them and (2) they performed average, so they may require more evaluations/careful reviewing of their file before a decision is reached.
And then, I related this to the Proof of Citizenship (PoC) status update:
I can confirm that the date of PoC update has nothing to do with an applicant's interview date, last name, nor when they uploaded their PoC – I have checked with friends who have theirs updated already. Also, the update has nothing to do with the document/item itself; it's the fact that the application's status has been updated. Since (according to my original thoughts above) stronger applicants are reviewed first, this may be why some people have their application's PoC updated, indicating that either (1) their file is about to be reviewed, or (2) their file has been reviewed and thus the update is taken place immediately after. This may further indicate that after stronger applicants have been reviewed, then Average interview applicants will be reviewed and thus their PoC will be updated, and then finally there will be one massive wave where all Below Average interview applicants will have their PoC updated. All in all, date of PoC update could correlate with an applicant's chance of being accepted.
Now that I've mentioned all these previous thoughts, this is what I'm thinking now: All the above is BS (lol) because these speculations are very likely to be wrong on many levels.
Firstly, if applicants are reviewed by a category/performance order (whether this be top to bottom or vice versa), this will clearly introduce bias in Admissions' process of accepting applicants. Furthermore, admissions is not on a rolling basis. As a result, it's very unlikely to accept a candidate during Admissions' first review of the applicant, simply because they haven't looked at all the rest yet. As a result, I think it makes more sense that they review candidates by some order (perhaps a code name like App001) which the order of has no correlation with the applicant's last name, interview date, etc, on multiple occasions. This also explains that the date of PoC update is random because it depends on the code name/application number. Whether this update correlates with application review, I'm not sure. Either some admissions assistant completes the PoC update separately from the review entirely, or he/she updates the status within the timing vicinity of the review.
Secondly, I now strongly believe that date of PoC update does not correlate with chances of being accepted. If this was the case, there would be a hint within the admissions process that allows candidates to determine the likelihood of being accepted before their decisions have been released. This could open Pandora's box and introduce a whole whack of problems and complaints.
Lastly, I don't think Below Average interview applicants are cut out immediately and I don't think that there is a variability in the time spent on reviewing a candidate's file dependant on their interview performance, simply because of two words: systematic process. I think it is more fair and it makes more sense that Admissions uses a systematic process in reviewing each applicant's file. This means that there is a consistent time spent reviewing an applicant's file, whether they are strong or not. Also, this means that Below Average interview applicants are still considered. Even though the interview stage is the interview stage, post-interview evaluations are holistic. Sure, interview is very important, but so are other things like reference letters, the MCAT, the applicant's ability to take on the rigorous MD curriculum, their motivation for medicine, their commitment to their community, and much, much more.
TL;DR: Keep calm and wait until May – we will never know until we actually know/find out in May.
¹ Some people withdrew their application, but this was the original reported number.