Yet more noise on emails from other Sean Conners on the Intarwebs

It appears that someone is wrong on the Internet, and if Hacker News is anything to go by, that person is me! Or rather, it might Justin Prime who wrote that Stack Exchange post about Gmail's possibly buggy support for periods in the local part of an email address.

But one thing not brought up in the Hacker News thread is that Gmail supports custom domains. So if some other Sean Conner were to have Gmail support email for example.org, then I would expect seanconner@example.org (our hypothetical Sean Conner who is not me) to be distinct from seanconner@gmail.com (which is me). And now I have to wonder if this might be a cause for some of the issues being reported? Google is a Leviathan system with millions of moving parts where a slight mishap (like a timeout or some lost packets on a database lookup or even a bug on a system not yet updated) causes email being delivered to seanconner@example.org to end up being delivered to seanconner@gmail.com.

I'm just trying to figure out what is more likely via Occam's razor, that a large, distributed system like Google has the occational hiccup, or a surprisingly large number of people forget their email addresses, especially given how important email addresses are for account recovery, password resets, and the like? I mean, it could be both. I'm just wondering what causes the larger number of incidents now that I'm seeing I not alone in all this.