Depends on the problem. If the problem is complex enough, say nutrition, then you see constantly changing narratives and theories and even competing ones in the present. There's no Best Solution™ way to nourish ourselves yet so people experiment and the top competing theories are being actively discussed and debated. Sure there are keto / vegan / paleo nuts out there but they're just test subjects really. Same argument can be said about software dev, there's no best language or best framework; or about ways to earn money, employment vs entrepreneurship is not a settled debate.
Can you name some problem that you feel has stagnated in the modern world?