It is lightweight, since you choose everything that is installed, sort of opt-in.
It has all the latest software.
It has "rolling releases" which means there is never a giant lost-weekend distribution upgrade.
It has the AUR (arch user repository) for just about any software ever.
No outdated packages, no ppa. No upgrade. Install is rough but it nails how simple the system is.
Ubuntu is a good starting point. But there is so much more.
"it should simply work" is not a given on any linux.
I'm not denigrating those distributions, there are lots of reasons to have a stable release without a lot of things changing (especially development).
It's just that changing lots of assumptions at once is fragile.
https://wiki.archlinux.org/index.php/PKGBUILD
For debian/ubuntu it is not as straightforward.