It's not really "invented". People get stuck on names way too much, forgetting these are simply placeholders, stopgap measures for a still incomplete, but evolving, understanding of nature.
Horrible. Explaining they are placeholders has actually eaten up a fair amount of my time. I'm betting I've probably spent days, if we total the hours up, explaining just that. (I like to go make science simple for people. Having to explain that it is a placeholder doesn't make it easy. So much wasted time.)
Still, gravitation waves were detected, while darks were not.