Something that's missing from this (otherwise great!) guide, that has puzzled me for a while - what's the point? What does this configuration actually gain you/AWS? My best guess is that private subnets are for DDOS protection, but that seems like something that would be better handled by throttling. Given the amount of complaints I've heard about how difficult VPC/Subnet setup is, why bother with it at all? Staving off IP address exhaustion?
Or, to ask it another way - what would be the downside of all your resources being in 1 single-Subnet VPC, spread evenly across AZs?
Or, to ask it another way - what would be the downside of all your resources being in 1 single-Subnet VPC, spread evenly across AZs?