> . . . or the problem is inherently complex.

You're close. Put another way, "inherent complexity is the problem."

What I mean by that is, the more your system is coupled, the more it is brittle.

Frankly, this is AWS's issue. It is too coupled: RDS relies on EBS, the console relies on both, etc. Any connection between two systems is a POF and must be architected to let those systems operate w/o that connection. This is why SMTP works the way it does. Real time service delivery isn't the problem, but counting on it is.

Uncouple all the things!