Question: is there a reason to use arch over something like kubuntu, or ubuntu? It seems like a difficult starting point

I think there's benefits with more recent packages, the package manager (pacman) and the AUR. But if you're new or don't have much experience then something like Ubuntu or Mint is a more sensible distro to begin with. At least they start with some applications and such so you know what's out there and how some things work.