HN user
I agree that deterministic would've been a better choice in this context.
I work on things close to Bazel, and the word "hermetic" gets thrown around a lot. And because of that, hermetic in my mind gets translated to "how an ideal build of a project should behave" (which obviously is wrong).
Last modified timestamps in source code are a bad idea and they make builds non-hermetic. Better to fix up those scenarios in code than work around them.
Irrespective you have a good point that touch does have side effects.
(Assuming no malicious intent from AWS) One of the reasons this is probably hard is probably because a lot of services didn't start out with having resource constraints.
So now if you support something like a "hard-billing-cap", every single service in AWS has to support it. That's a huge stone to move - it could even be in the works today.