If you want to read more, it was called "EC2 Classic" (well, it wasn't called that before VPCs were launched!). There was a discussion about it being retired on HN here: https://news.ycombinator.com/item?id=27988964

It was unironically pretty convenient. You had to manually set up NAT in a VPC for a long time (until they made NAT gateways) and some other early quirks were a pain in the ass. EC2 "classic" still had security groups and it was pretty effortless otherwise for a small deployment since it's connected to the internet from the start.

I was also surprised by this, does that mean it used to be impossible to not have a publicly routable IP in AWS?

My recollection is that for a period of time, as a part of the internal “Move to AWS” (MAWS) campaign, the entire retail business ran within a single VPC. A lot has changed!

Thank you, I'm glad you liked the book!! That was a fun project, and I learned a lot while writing it.

are you planning on turning this into a book also? if so I'd be interested. the blog posts were very helpful :)