Alternate explanation: Xe, Rachel, and quite a few other people (patio11? tptacek?) have been at this a while, have worked with a lot of people, and have consis

Alternate explanation: Xe, Rachel, and quite a few other people (patio11? tptacek?) have been at this a while, have worked with a lot of people, and have consistently put out high quality content. They put in the time to build an audience. It's not that "the system" knows them as valuable, it's that people have gotten to know them over time and trust them. These are people, for me, whose articles I'll always make time for. I suspect a lot of HNers feel similar, so that's a lot of upvotes, so that's a lot of frontpage hits.