But the reason they are metaorigins is that a single actual origin -- changes the genre. Everyone practices magic a la Doctor Strange -- fantasy! Everyone's wearing a powersuit a la Iron Man -- SF! Etc.
So what is need is an origin of superhuman origins. Something that can create situations where different powers are manifested in different ways. Like DC's metagene, just awaiting the particular accident to bring out some different superhero.
Not that the relationship is always rational.