Part of the problem is that a large number of site pull in services, re-targeting, AB-test, and weird Javascript in general. These things are pulled in without questioning or demanding an SLA or putting in an easy way of pulling them back out. Even if you don't use AWS yourself, you can be sure that some third party you rely on is deploying on EC2. Of cause they'll never tell you that.

For most new stuff, we require that it can be loaded with something like Google Tag Manager or UberTag, so we can quickly disable them when they fail.

It doesn't help that Amazons status page isn't all that good and sometimes doesn't seem to actually reflect the true state of their service.