"Why don't you like homebrew?"

I've blogged about some of my problems with Homebrew. Generally speaking, Homebrew is a triumph of marketing and beautiful web design over technical merits (there are better options for macOS, but none nearly as popular as brew).

The blog post: http://inthebox.webmin.com/homebrew-package-installation-for...

I get that it's easy and lots of people like it, so I mostly try to hold my tongue, but every once in a while I'll see someone suggest something crazy like using Homebrew on Linux (where there is an embarrassment of good and even great package management options) and it makes me shudder. I'm not saying don't use Homebrew on your macOS system if it makes your life easier. I just would never consider it for a production system of any sort. I'm even kinda mistrustful of it on developer workstations (though there are plenty of similarly scary practices in the node/npm, rubygems, etc. worlds, so that ship has kinda sailed and I am resolved to just watch it all unfold).

"What happened to wanting simple tools that do one thing and one thing right?"

I still want that. Doing one thing right in this case means doing more than what packages on macOS or Windows do. One can argue about the complexity of rpm+yum or dpkg+apt, and it's likely that one could come up with simpler and more reliable implementations today, but if you want them to be more focused, I have to ask which feature(s) you'd remove? Dependency resolution? That one's a really complicated feature; a lot of code, and it's been reimplemented multiple times for rpm (up2date, yum, and now dnf). Surely, we can just leave that out. Or, perhaps the notion of a software repository? Is it really necessary for the package manager to download the software for us? I mean, I have a web browser and wget or curl. Verification of packages and the files they install, do we really need it? Can't we just assume that our request to the website won't be tampered with, and that what we're downloading has been vouched for by a party we trust? I dunno...I'm not really seeing a thing we can get rid of without making Linux as dumb as macOS or Windows.

"Don't we want package managers to only manage packages, to decouple them as much as possible from the rest of the operating system, and leave system configuration management to other tools?"

This is the strangest question, to me. Why on earth would we want the OS outside of the package manager? Why would we want to only verify packages that aren't part of the core OS? This is why Linux is so vastly superior to Windows and macOS on this one front. I'm having a hard time thinking of why having the package manager completely ignorant of the core OS would be a good thing. What benefit do you believe that would provide?

And, NixOS does not meet the description you've given. The OS is built with nix the package manager. Running nix as a standalone package manager on macOS does have the failing you've mentioned, but that's not the fault of nix. And, yes, nix is a better option for macOS than brew, but the package selection is much smaller and not as up to date in the general case...so maybe worse is better, in that case.

I get a bit ranty about package management. I spend a lot of time working with them (as a packager, software builder, distributor, etc.) and have strong opinions. But, I believe those strong opinions are backed by at least better than average experience.