Sure, that would be even better. But how would that even look?
In the best case applicants needs to apply multiple companies. Companies need to interview multiple applicants and have a way to compare those applicants.
Those are the most basic constraints I can think of. How do you make that cost tens of hours for each round?
You would have to stop optimizing people to hell and back and start committing to a few at a time. Sounds like a really good idea to me.