As a guess, SQL and noSQL are different tools good for different things and before noSQL people were trying to hammer their document-store shaped peg into a rel

As a guess, SQL and noSQL are different tools good for different things and before noSQL people were trying to hammer their document-store shaped peg into a relational-database shaped hole. To speculate, noSQL key-value stores became very popular because they allow you to model imperfectly defined situations, and to update that model quicker than in traditional relational-database type situations. Consider the difference between writing some classes in Java, or bunging everything into a dict in Python. The Java solution could be more formal and well documented, but a pain in the ass if the model changes significantly. The Python solution is a bit more janky and probably sluggish, but can adapt quicker. I think there are more people in things like research, self-teaching, iterative game dev, and exploratory startups that value the adaptability than there are in things like old school business consultancy for whom the underlying model might be static and well described.