The, uh, “Arch” installation on one of my laptops is from 2016 (the oldest one had bad RAM so suffered from file corruption and needed a reinstall last year). Other people will have older installations.
This is one of the key benefits of a well-maintained rolling-release distribution: it just keeps rolling.
Of course, if you regularly install and remove a load of random stuff then configuration files might be left behind, and reconfiguring things or not actively maintaining things then something might break, so wiping then might make sense. However, that sort of testing is better done in a VM so it’s isolated and trivial to wipe.