There's an explanation somewhere as to why. It has to do with "not breaking" stuff relying on it. So I guess it only answers "why we won't fix it".

Anyway, I don't think this is enough. Or I guess it only works to stop the trigger during install? I have the NO_AUTO_UPDATE set up, and recently needed to update (or upgrade? who knows) a single package and it somehow ended up with Homebrew working for over two hours. I saw it installing python at least two times.

That's not a proper explanation IMO. The thing is - all these settings are introduced "quietly" as new defaults and you have to opt out. So one day you decide to upgrade a package, brew updates itself, and then starts doing all these things that weren't present before (and are most likely not needed at all). It's very annoying, and a dark pattern to say the least.

Maybe also these, to limit other annoyances:

  export HOMEBREW_NO_EMOJI=1
  export HOMEBREW_NO_ENV_HINTS=1
  export HOMEBREW_NO_INSTALL_CLEANUP=1

Out of curiosty, why the last one? If you update a package, generally you don't need the old version, why would you keep it around? I can imagine this being useful in some edge cases, but as a global setting, I'm not so sure.

I got bitten by broken upgrades in the past, when you were still able to simply "brew switch" to the old version if it was there. In addition the cleanup time is annoying when upgrading a lot of packages, so I kept the setting.

because the fundamental ethos of homebrew and a lot of “modern” tools is to prioritize the conservation of attention. Aka “don’t make me think“ which, ironically, appears to often be adopted, not only on behalf of users, but at a meta level, so things which might well deserve prompts are simply pre-configured.

some charity is due here, because this is the culture, and also because for any software tool of sufficient complexity, there is always more to think about than attention to give. But the culture could use more improvement and reflection here.