Can someone ELI5 no one ever thought to look for this in the first place? Viruses cause so many illnesses, would it be possible to release (possibly benign) bac

Can someone ELI5 no one ever thought to look for this in the first place? Viruses cause so many illnesses, would it be possible to release (possibly benign) bacteria that eat the illness causing virus into the body (assuming the bacteria themselves aren't attacked by the immune system)? Also, is this an accidental discovery? Having read the article, I am under the impression that it is a bit of a chance find.