> Being able to roll it back isn't really a difference, you can revert to the previous version of a package too.

Sometimes. In a world in which customers are increasingly adopting immutable infrastructure patterns and (contrary to best practice) using Launch Templates with symbolic references to `latest` versions of AMIs, this isn't always easy.

> There is inherently a trade off between keeping the system online, keeping the system patched and testing the patch before applying it.

On this we agree 100%.