Originally Posted by
Inb4whales
Consider it as a tierlist more than a rarity list.
SSR pull rate is low, sure. But it doesn't mean that their power should not be divided into layers of tiers.
In any given game that is not chess or checkers and you're allowed to choose characters or varying inherent abilities, tier list will always exist to show which of the characters simply perform better in most situations over the others.
One example being a comparison of two light element SSRs, Sol and the upcoming Raphael for example.
If you use the JP wiki (which I can't friggin post a link here), you'll notice that she is worse than Sol in pretty much every category except Max ATK stat with 370 more stat points than Sol.