[indigomm]

> I doubt it, since outages and their effects are nuanced.

Your point here deserves highlighting. A failure such as a zone failing is nowadays a relatively simple problem to have. But cloud services do have bugs, internal limits or partial failures that are much more complex. They often require support assistance, which is where the expertise of their staff comes into play. Having a single provider that you know well and trust is better than having multiple providers where you need to keep track of disparate issues.