... but really its not too far off, is it?
Soul Gems ---> Sailor Crystals: The Sailor Crystals practically serve as a Sailor Senshi's soul, as well as power source. Yaten even stated that the physical body is unimportant, all that matters is the Sailor Crystal.
Witches ---> Youma: While most of the Sailor Moon monsters are beyond goofy (I'm lookin at you Ponko), there are plenty that can be genuinely terrifying and dangerous. Also the Sailor Senshi do die, and in rather harsh ways. Sure they come back to life eventually, but that doesn't make their deaths any less horrifying to experience.
So, Sailor Moon and Madoka Magica show a very similar set of events, just with one emphasizing despair and fear