The unreliability claim is driven by two factors.

1. When aws deploys changes they run through a pipeline which pushes change to regions one at a time. Most services start with us-east-1 first.

2. us-east-1 is MASSIVE and considerably larger than the next largest region. There's no public numbers but I wouldn't be surprised if it was 50% of their global capacity. An outage in any other region never hits the news.

I don't think its fair to dismiss a lot of anecdotal evidence, much of human experience is based off of it, and just being anecdotal doesn't make it incorrect. For those of us using aws for the last decade, there have been a handful of outages that are pretty hard to forget. Often those same engineers have services in other regions - so we witness these things going down more frequently in us-east-1. Now can I say definitively that us-east-1 goes down the most - nope. Have I had 4 outages in us-east-1 I can remember and only 1-2 us-west-2, yep.