One of our customers does use AWS, but only as a third backup behind their two physical datacenters.
The problem is, their main website uses a whole bunch of javascript widgets, some of which, yup, you've guessed it, were hosted in the failed region of AWS. So, their home page would only load up to a certain point, and then would sit, waiting for the third party javascript that would never load.
So, even if, as the sysadmins, you've done all you can to make the site redundant and fault tolerant, never underestimate the opportunity for the developers to fsck it right up.
Biting the hand that feeds IT
