I don’t necessarily agree with that. I think the idea of draining life and healing it ties in well with the themes of selfishness and selflessness, which are central to the Saga. I think what is unique to the Dyad, though, is the ability of resurrection.

In the prequels, Anakin had a vision that Padmé would die. To him, that meant her dying was inevitable, and he needed a power beyond just healing.

And just because others have not used this ability in the films beforehand doesn’t mean it didn’t exist. Perhaps it was a technique lost and was rediscovered by Rey in the ancient texts. Or, the waning and waxing of the Force’s strength over generations has an effect on people’s ability to perform it.

And regardless if you cut the power out of IX, it won’t change the fact that Baby Yoda uses the power in the Mandalorian. And maybe he can do it because it is a child, and children have been shown to have an innate connection to the Force, just like the Dyad is shown to have in IX.