[dba-SQLServer] NoSQL etc.

I have downloaded and installed a couple of these but not yet discovered
any practical (from my POV) applications of this. From what I can gather
from the ReadMes etc., they are basically a key-value collection, which it
would seem is designed for web-apps whose principal task is to rapidly and
scalably retrieve values from the db. It's not readily apparent how this
might be applied to a relational database (say, Customers, Orders,
OrderDetails and Products).

Does anyone have any insight into actual use of these technologies?

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