Ask HN: Thoughts on /etc/hosts instead of DNS for production applications?

Hi HN,

"It's always DNS" is a theme we're all familiar with when it comes to outages. I understand why DNS is critical for most users. But for applications that are managed/deployed using an "Infrastructure as Code" system, where changes can, and should always be pushed in a way that treats the changes the same way code changes are treated (Devops and all that), is there any harm with using /etc/hosts files everywhere?

That way name-to-ip association changes benefit from IaC, and DNS related instabilities are minimized. Of course, I am assuming the name-to-ip association is under the control of the system's engineers to begin with, for every other use case DNS can and should still be used.

Why aren't cloud providers and FAANGs doing this already, where saving costs by eliminating things like DNS request traffic and CPU cycles is encouraged?