This is definitely something Nix is very good at, but it's not a problem with Arch. Staying up to date with upstream is basically the point of the distro, so if you're going to postpone an update for a year you should be using something else.
> We told you Arch would be bad at this
does not refute (or even contradict)
> Arch is bad at this
The cost of Arch's KISS philosophy is a system that is uniquely brittle among Linux distros in a number of ways, and Arch users are totally unwilling to admit this except in the form of blaming users for having bad experiences.