There are other examples we don't see either. They experimented with adding Blessed Shield to Rolands for instance, but the result proved too taxing for the servers - Rolands' lightning-fast attack speed combined with that splitting rune and resource-free BS from Gyrfalcon meant thousands of effects being generated on screen at once, and they ultimately had to roll that back.

Which leads me of course to another point - some abilities are just plain cool, so you want them to be in the game, but making them so powerful that everyone considers them viable has deleterious effects. Leaving them weaker and niche keeps them around and fun for those who want to play for fun, while letting them be safely ignored by those with more of a progression focus in mind.