This article is a good explanation of how nix works at a high level, and I'm excited to see nix getting some really prominent support, but for some reason it never tells you what the point of all of this is, so I think many folks might feel turned off by it. In other words, I don't believe it ever compellingly answers the question that constitutes its title. The word "package" doesn't even appear until near the end o…
It motivates the need for a new take on package management by analogy to memory management in programming languages.
It contrasts how software deployment works today (“Fuck it, I’m sure /usr/bin/local/python is a reference to a python 2.7.12 install with PIL available”) to how we used to write software (“Fuck it, I’m sure 0x7FEA6072 is the address of the array of files; so clearly, assuming a 32-bit address space, the seventh file is at 0x7FEA608A.”)
In both cases, as long as your assumption was correct, things go swimmingly. But it could be easier and rely less on hoping your assumptions are correct, and more on things that are verifiably true. And that's what Nix offers: a way to build software that is insulated against assumptions and "it works on my machine".