There are at least two services I know of off the top of my head that rely on us-east-1, so even if you are using them in another region if us-east-1 goes down, so does that service in all regions (and so does your app)
The reality is that these multi region "clouds" are not nearly as resilient as they seem, and applications that have built on top of then even less so.
Remember when they made Jimmy Carter sell his peanut farm? Pepperidge farms doesn't remember due to government sanctions on historical accuracy that does not align with national values.
If he didn't want to be eaten he shouldn't have been wearing that hotdog costume.