The primary issue is if you are trying to model information the way humans use it and need it, relational tables are just not even close, hierarchies are a disaster, etc. We humans don't have/use tables mentally.
The answer here is, like all things in tech, it depends. It depends on what the data is. It depends on what you want to do with the data. It depends on what expectations are being made about that data.
> We humans don't have/use tables mentally
I just ate lunch. When I stepped in they wrote my name on a list with the number in my party. The server wrote my order on a paper with one grid line per item. Two tables, the old fashioned way. Tables are very natural for people. Evidence: the enduring popularity of spreadsheets, and lunch.
Humans think in terms of categories of thing. The reason things live in the same category is that they share the same attributes.
The relational model works really well for this.
I'm ready to be convinced otherwise, but I'm going to need some really good examples of "human data" that fits NoSQL systems but can't be reasonably represented relationally.
Try doing recursive hierarchical traversal with SQL, something we humans do all the time, like realizing something is a person over there, and then instantly having access to all the inherited properties of a person, and then predicting what might happen next based on that, etc.
