Why OpenRC and not SysV?
All Artix packaging is SystemD free?
Artix has 5 different init systems you can choose from (not only openrc). SysV is not one of them because it is awful and you really should not use it.
Yes, that's the entire point.
sysvinit had flaws and had to be replaced. Some of them are listed in this article, which advocates the use of s6: https://skarnet.org/software/s6/why.html
Any of the (currently) 5 init systems supported by Artix are better than both sysvinit and systemd. Take your pick among them, it doesn't have to be OpenRC.