[scubbo]

Having _everything_ on a single AZ of AWS is, indeed, a problem.

Having everything well-architected on AWS is...well, it's a problem for reasons of monopoly and cost, but it's not a problem for availability.

[Nextgrid]

Certain "global" AWS services depend on a specific region (us-east-1 if I recall right) so if that goes down you could be in trouble.