Postinstall scripts run at install time, with installer's privileges.
Its childish to believe that because you can't fix everything you shouldn't fix anything. Defense in depth.
You don't need to test a compromised package to have it execute code. Importing it anywhere in your tests is enough, even transitively.
It's for sure less likely to run but I doubt it's significantly different in practice.
https://www.stepsecurity.io/blog/mini-shai-hulud-is-back-a-s...
This is definitely going to affect any packages that need to link to native code and/or compile shims, but these are very few.
But so is the regular code in those packages! It won't run at install time, but something in there will run -- otherwise it wouldn't have been included in the dependencies.
Thinking that eliminating post-install scripts will have more than a momentary impact on exploitation rates is a sign of not thinking the issue through. Unfortunately the issue is much more nuanced than TFA implies -- it's not at all a case of "Let's just stop putting the wings-fall-off button next to the light switch", it's that the thing we want to prevent (other people's bad code running on our box) cannot be distinguished from the thing we want (other people's good code running on our box) without a whole lot of painstaking manual effort, and avoiding painstaking manual effort is the only reason we even consider running other people's code in the first place.