If what I hear it’s true than once a NixOS user is up and running adding additional packages and up-streaming them appears to be a fairly simple process.
Something like Arch has ~10,000 packages in the main repo and the AUR has ~70,000 packages. It’s hard to get something into the Arch repo, very easy to get something into the AUR. NixOS seems like it may be a middle ground where by the time someone can grok the system they should only be a step or two away from contributing to it.
Linux gives you freedom.
Freedom lets you break stuff.
If, like Windows or MacOSyou just use it as intended by official support, it should be fine. If you start just adding everything and anything from anyone you’re gonna break stuff.
Other stuff is made to be idiot proof, Linux is not.