...is that when people say this, the subtext usually is, "...but if we ever throw up our dog-food, we expect someone else to go grab the mop". AWS customers have long been on the brunt end of this for AWS services that rely on other AWS services. Did service X fail because service Y that it uses suffered a rate-limit or some other outage? "Sorry customer, to hear about YOUR problem. Here's some suggestions to fix YOUR problem." Blah blah blah...
Now AWS has done it to themselves. There needs to be paradigm shift to "own my failures, don't pass the buck" from a service perspective. Things need to work on days when it's pouring rain just like on days when the sun is shining. Having a brittle supply chain like this shouldn't be acceptable. Each service has to have a back-up plan whenever possible. It will lead to more robust architecture design patterns when creating such services, even if it makes things harder for AWS.