You can say the same thing about Phase 1 to 3 as well.

The reality is every theraputic has some kind of negative side effect, which may reduce the incentive for it to be productionized becuase the whole point about medicine is harm reduction.

Passing the hurdle of being viable in mice is a major hurdle because in most cases, experiments fail. And if it's efficacy is proven in mice, it shows viability in a specific approach and justifies investing the hundreds of millions of dollars in trying to bring something to Phase 3.