Let me ask you something: doesn't it bother you that something like Nix is necessary for the problems Nix claims to solve? Why is a system so fragile as to require what Nix provides?

If you stay in the bleeding edge some setups might break. E.g. package A doesn't work with library B anymore unless you switch back to another version.

I have very rarely experienced this problem, and in 8 years time I have never had to roll back any critical packages like the kernel, firefox, emacs or any system utilities.

It's not something that bothers me because it's so rare, and I understand it's the product of very complicated setups and bleeding edge configurations.

Nix is mostly valuable for simple declarative configurations, the ability to alter package build recipes quickly, and for package and setup reproducibility.

That's my whole point though: why does this library conflict occur at all? Why do you need such a convoluted tool just to have a reproducible setup? Doesn't something about the nature of that situation seem off to you? Like, Nix solves a problem that maybe only exists because the system itself is fundamentally flawed?